ItM 


V 


^>. 


IMAGE  EVALUATION 
TEST  TARGET  (MT-S) 


% 


4- 


1.0 


■  30 


i^  m 


M  t^m 


!.l 


2.2 


.25 


li£    ililO 


1.8 


1114.  111.6 


i? 


»^ 


7^^      > 


/ 


,3%;.   ^     -V      >X 


>P 


^>' 
"> 


.** 


'm- 


■4 


V 


<? 


w 


Photographic 

Sciences 
Corporation 


fV 


"^q 


,v 


^N 


??' 


^<^ 


V 


A 

/<^, 


1*. 


o 


%' 


23  WiST  MAtt4  STREIT 

WEBSTER,  N.Y.  14580 

(716)  !  72-4503 


^ 


'^ 


CIHM/ICMH 
Microfiche 


CIHM/ICMH 
Collection  de 
microfiches. 


Canadian  Institute  for  Historjcal  Microreproductions  /  Institut  Canadian  de  microieproductions  historiques 


Technical  and  Bibliographic  Notes/Notes  techniques  et  bibliographiques 


The  Institute  has  attempted  to  obtain  the  best 
origir.-3l  copy  available  for  filming.  Features  of  this 
copy  which  may  be  bibliographically  unique, 
which  may  alter  any  of  the  images  in  the 
reproduction,  or  which  may  significantly  change 
the  usual  method  of  filming,  are  checked  below. 


D 


n 


n 


n 


Coloured  covers/ 
Couverture  de  couleur 


I      ]    Covers  damaged/ 


Couverture  endommagde 

Covers  restored  and/or  laminateJ/ 
Couverture  restaurde  et/ou  ;'ellicul6e 


□    Cover  title  missing/ 
Le  tit 


titre  de  couverture  manque 


I      I    Coloured  maps/ 


artes  g^ographiques  en  couleur 


ni° 


Coloured  ink  (i.e.  other  than  blue  or  black)/ 
ere  de  couleur  (i.e.  autre  que  bleue  ou  noire) 


I      I    Coloured  plates  and/or  illustrations/ 


Planches  et/ou  illustrations  en  couleur 

Bound  with  other  material/ 
helid  avec  d'c^'tres  documents 

Tight  binding  may  cause  shadows  or  distortion 
along  interior  margin/ 

La  reliure  serree  peut  causet'  de  I'ombre  ou  de  la 
distortion  le  long  de  la  marge  intdrieure 

Blank  leaves  added  during  restoration  may 
appear  within  the  text.  Whenever  possible,  these 
have  been  omitted  from  filming/ 
II  se  peut  que  cbrtainas  pages  blanches  ajoutdes 
lors  d'une  restauration  apparaissent  dans  le  texte, 
mais,  lorsque  cela  dtait  possible,  ces  pages  n'ont 
pas  6t6  filmdes. 


L'Institut  a  microfilm^  le  meilleur  exemplaire 
qu'il  lui  a  6t6  possible  de  se  procurer.  Les  details 
de  cat  exemplafre  qui  sont  peut-dtre  uniques  du 
point  de  vue  bibliographique,  qui  peuvent  modifier 
une  image  reproduite,  ou  qui  peuvent  exiger  une 
modification  dans  la  methods  normale  de  filmage 
sont  indiquds  ci-dessous. 


I      I    Coloured  pages/ 


n 

n 


n 


Pages  de  couleur 

Pages  damaged/ 
Pages  endommagdes 

Pages  restored  and/or  laminated/ 
Pages  restauries  et/ou  pellicul^es 

Pages  discoloured,  stained  or  foxed/ 
Pages  d6color6es,  tachetdes  ou  piqudes 

Pages  detached/ 
Pages  d6tach6es 


r~7]    Showthrough/ 


Transparence 

Quality  of  print  varies/ 
Qualixd  indgale  de  I'impression 

Includes  supplementary  material/ 
Comprend  du  materiel  supplementaire 

Only  edition  available/ 
Seule  Edition  disponible 


Pages  wholly  or  partially  obscured  by  errata 
slips,  tissues,  etc.,  have  been  refilmed  to 
ensure  the  best  possible  image/ 
Les  pages  totalement  ou  partiellement 
obscurcies  par  un  feuillet  d'errata,  une  pelure, 
etc.,  ont  6t6  filmdes  d  nouveau  de  fapon  d 
obtenir  la  meilleure  image  possible. 


D 


Additional  comments:/ 
Commentaires  suppldmentaires; 


This  item  is  filmed  at  the  rgHuction  ratio  checked  below/ 

Ce  document  est  film6  au  taux  de  reduction  indiqui  ci-dessous. 

10X  14X  18X  22X 


26X 


SOX 


y 

12X 


16X 


20X 


24X 


28X 


32X 


The  copy  filmed  here  has  been  reproduced  thanks 
to  the  generosity  of: 

Library 

EnvironmMit  Canada 
Chaudiira  Branch 
(Parks  Canada) 


L'exempiaire  film6  fut '  «oroduit  grAce  A  la 
g6n6ro8it6  de: 

BibliotMqua 
Environnamant  Canada 
Succumla  ChtudlAra 
(Pares  Canada) 


The  images  appearing  here  are  the  best  quality 
possibiti  considering  the  condition  and  legibility 
of  the  original  copy  and  in  keeping  with  the 
filming  contract  specifications. 


Les  images  suivantes  ont  6t4  reproduites  avec  le 
plus  grand  soin,  compte  tenu  de  la  condition  et 
de  la  nettetd  de  I'axemplaire  fiimd,  et  en 
conformit<&  avec  les  conditions  du  contrat  de 
filmage. 


Original  copies  in  printed  paoer  covers  are  filmed 
beginning  with  the  front  cover  and  ending  on 
the  last  page  with  a  printed  or  illustrated  impres- 
sion, or  the  back  cover  when  appropriate.  All 
other  original  copies  are  filmed  beginning  on  tha 
first  page  with  a  printed  or  illustrated  impres- 
sion, and  ending  on  the  last  page  with  a  printed 
or  illustrated  impression. 


Les  exemplaires  originaux  dont  la  couverture  en 
papier  est  imprim6e  sont  film6s  en  commenpant 
par  le  premier  plat  et  en  terminant  soit  par  la 
dernidre  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustration,  soit  par  le  second 
plat,  salon  le  cas.  Tous  les  autres  exemplaires 
originbux  sont  film6s  en  cc^menpant  par  la 
premidre  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustration  et  en  terminant  par 
la  dernidre  page  qui  comporte  une  telle 
empreinte. 


The  last  recorded  frame  on  each  microfiche 
shall  contain  the  symbol  — ^>  (meaning  "CON- 
TINUED "),  or  the  symbol  V  (meaning  "END"), 
whichever  ap;?lies 


Un  des  symboles  suivants  apparaitra  sur  la 
dernidre  image  de  cheque  microfiche,  selon  le 
cas:  le  symbole  -h^  signifie  "A  SUIVRE",  Is 
symbols  V  signifie  "FIN". 


Maps,  plates,  charts,  etc.,  may  be  filmed  at 
different  reduction  ratios.  Those  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bottom,  as  many  frames  as 
required.  The  following  diagrams  illustrate  the 
method: 


Les  cartes,  planches,  tableaux,  etc.,  peuvent  Atre 
filmAs  ^  des  taux  de  reduction  diffArents. 
Lorsque  le  document  est  trop  grand  pour  dtre 
reproduit  en  un  seul  clich6,  il  est  film6  A  partir 
de  Tangle  supArieur  gauche,  de  gauche  d  droite, 
ct  de  haut  en  bas,  en  prenant  le  nombre 
d'images  ndcessaire.  Les  diagrammes  suivants 
ii:ustrent  la  mdthode. 


1 

2 

3 

1 

2 

3 

4 

5 

6 

Glaciers  of  North  America, 


Plate  l. 


Sketcli  map  showing  the  distribution  of  goino  of  the  better-known  sUiciors  of  North  America 
Southern  limit  of  Pleistocene  ice  sheet  intlicateil  by  a  heavy  broken  line. 


o        •      I 


•  ••       •  I 
■  •  •      •     • 

•  •    t     •  •    • 


• .    •    , 

•    «    •  •    • 
'     •  •        • 


•    c 


•      • 


•  •    «       t    t  I 


•  •       •         •••t« 

•  *       •       •      •     •  I  I 


•    •     <   t    t       1    , 
•     •    •  •    • 


•  •      I  •  ■ 


GLACIERS 


OF 


]^OETH    AMEEICA 


A  READING  LESSON  FOR  STUDENTS  OF 
GEOGRAPHY  AND  GEOLOGY 


BT 

ISRAEL  C.  RUSSELL 

PROFESSOR  OF  GEOLOGY,  rNIVKRSITY  OF  MirHIOAK.  AUTHOR  OW 
"LAKES  OF  NORTH   AMERICA,"  ETC. 


GiNN  & 'Compact''/'     ' 


«    I'        # 


■>        t      . 

3  »    »   I 

IS        J        »  •• 


» • .     ^       I 


r 

•  Re 


Copyright,  I897 
By  ISRAEL  O.  RUSSELL 


ALL  AIOHTS  RESERVED 
30.8 


•  « 

«  •  « 


•:: 


,        ^     GINN'   ,V   COMfANY  .  PRO. 


•  •• 

•  • 

»•  • 

*      • 
«  •  ■ 


TO   THE   EEADER. 


-*oj»-:o<- 


Until  within  the  pafit  few  years,  nearly  all  current  knowledge  of 
glaciei-s  was  based  on  the  study  of  those  of  the  Alps.  Practically  all 
theories  of  the  orrgin,  growth,  motion,  etc.,  of  glaciera  were  inspired  from 
the  same  source.  An  enlargement  of  the  field  of  study,  however,  has 
shown  not  only  that  glaciers  of  the  same  type  as  those  of  Switzerland  exist 
in  many  other  lands,  but  in  numerous  instances  are  larger  and  present 
greater  divei'sity ;  and  besides,  additional  types  or  "  genera  "  have  been 
discovered  that  are  not  represented  in  Europe  or  in  fact  on  any  of  the 
three  continents  of  the  Eastern  Hemisphere. 

As  geological  and  geographical  explorations  have  been  extended,  it 
has  been  found  that  North  America  is  not  only  a  favorable  field  for  the 
growth  of  these  twin  sciences,  but  in  many  ways  furnishes  the  best 
example  of  continental  development  that  has  as  yet  been  studied.  Strange 
as  it  may  appear  in  the  face  of  the  overshadowing  popular  interest  that 
centers  in  the  glaciers  of  the  Alps,  North  America  offers  more  favorable 
tonditions  for  the  study  of  existing  glaciers  and  of  the  records  of  ancient 
ice  sheets  than  any  other  continent.  Of  each  of  the  three  leading  tyj^es 
of  glaciers  thus  far  reorganized,  namely,  the  alpine,  piedmont,  and  conti- 
nental, North  America  furnishes  magnificent  examples.  In  fact  there  is 
no  other  continent,  except  the  little  known  region  about  the  South  Pole, 
in  which  other  than  the  alpine  type  of  glaciers  exist.  Of  alpine  glaciers 
representatives  occur  in  North  America  in  abundance  and  in  great  variety, 
ranging  from  the  "  pocket  editions  "  about  the  summits  of  the  High  Sierra, 
California,  to  the  magnificent  Seward  glacier,  Alaska,  the  largest  river  of 
ice  flowing  from  a  mountain  group  that  has  yet  been  disco^Aered.  Of 
piedmont  glaciera,  the  type  specimen,  so  to  speak,  and  the  only  one  of 
the  class  yet  explored,  is  the  great  ice  sheet  that  intervenes  between 


IV 


TO   THE    UEAUKU. 


Mount  St.  Elias  ami  the  Pacific,  known  as  tlie  Malaspina  glacier.  The 
still  larger  continental  glaciera  —  of  the  nature  of  tlie  ice  sheet  that 
formerly  covered  the  northern  half  of  North  America,  and  the  smaller 
sheet  beneath  which  northwestern  Europe  was  once  buried  —  are  repre- 
sented in  the  Northern  Hemisphere  at  the  present  time  by  a  single 
example  in  Greenland. 

The  magnificence  of  the  field  for  glacial  study  in  North  America  has 
only  l)e3n  appreciated  within  recent  years,  and  is  still  unrecognized  out- 
side of  a  limited  circle  of  special  students.  By  gathering  in  the  book 
before  you  the  information  now  available  concerning  North  American 
glaciera,  it  has  been  my  aim  not  only  to  report  the  present  condition  in 
this  country  of  an  important  branch  of  geological  and  geographical  enquiry, 
but  to  make  you  familiar  with  glacial  phenomena  in  general  and  stimu- 
late a  (hirst  for  fresh  explorations  and  renewed  study  along  an  almost 
untrodden  path. 

From  what  I  have  seen  personally  of  the  glaciers  of  the  United  States 
and  Canada,  and  from  glimpses  obtained  in  previous  years  of  thooe  of 
Switzerland  and  New  Zealand,  as  well  as  from  all  that  I  have  read  con- 
cerning the  ice  fields  of  other  lands,  I  think  I  can  affirm,  without  fear  of 
contradiction,  that  southern  Alaska  and  adjacent  portions  of  Canada  offer 
one  of  the  most  promising  fields  for  glacial  study  that  can  be  found.  I 
shall  be  more  than  repaid  for  the  labor  expended  in  writing  this  little 
book  if  it  leads  even  indirectly  to  a  renewal  of  the  explorations  now  barely 
begun  in  that  instructive,  highly  picturesque,  and  most  attractive  region. 


Israel  C.  Russell. 


co:n^teis^ts, 


t 


CHAI'TEU   I. 

iNTRODt'CTION 

A  typical  glacier.  —  Variations  from  the  type.  —  The  term  "  glacier  "  indeflnlte. 

LkaIMNO    ClIAKAtTKlUSTICS   OK    'jI-AClERS 

Mode  of  nccuimilation.  -  Hnu-  of  flow.  -  Three  types  of  glaciers  ;  alpine,  piedmont,  and 
continental.—  Divisions  of  tin-  surface  of  a  glacier,  n<5ve  and  glacier  i>roper.  -  Handed 
structure.-  ({lacier  grain.  -  Moraines :  lateral,  medial,  terminal,  and  frontal.  -  Crevasses. 
—  The  starting  of  ercvussfs.  —  IJergsclirunds.  —  Ice  falls.  —  Marginal  crevasses.  —  Surface 
features :  glaci.-r  tables,  sand  cones,  debris  pyramids.  —  .Melting  and  drainage ;  super- 
glacial  and  subglacial  streams.  —  Characteristics  of  streams  Uowing  from  glaciers. 

WiiA     IS  A  Glacier  ?      .        .        . 

Glacial  Ahrasion 

Worn  and  striated  rock  surfaces. 

Smoothed  and  Striated  Siriaces  not  Produced  by  Glaciers 

Scorings  made  by  river  and  lake  ice  and  by  ice  ttoes. 
Special  Featlres  of  Glaciated  Surfaces 

Semilunar  cracks,  chatter  marks,  disrupted  gouges,  etc. 

Glacial  Deposits ,  _       . 

Lateral  moraines.  -  Perched  blocks.  -  Terminal  moraines.  -  Morainal  embankments. 
—  Frontal  moraines.  -  Interlobate  moraines.  —  Till.  —  Boulder  clay.  —  Drumlins. 

Glacial  Sediments 

•        •        •        •        •        •        .        .        , 

Osars.  —  Kanies.  —  Sand  and  gravel  plains. 
Changes  in  Topography  Produced  by  Glaciers 

CHAPTER   II. 

General  Distribution  of  the  Glaciers  of  North  America 

Cordilleran  region.  —  Greenland  region. 


PAGE 
1 


16 
18 

19 

20 

22 

28 
30 

82 


CHAPTEU  III. 

Glaciers  of  the  Sierra  Nevada ^  07 

The  High  Sierra „_ 

Southern  limit  of  glaciers  in  the  United  States, 

Mount  Dana  Glacier \  „,. 

Mount  Lyell  Glacier  ....  .n 

...  40 

Parker  Creek  Glacier    ...  .,, 

•    • 41 


VI 


CONTENT8. 


ClUHACTEKISTICS   OK   TIIK    GlaCIKHS   OF   THE    IIuJH    SlEHHA 

Wv.%.-Cr«v««8e«._  Lh, atl....  or  rll.lK„.e.l  «t,uctur«.  -Dirt' b.ui.l..-«iacler 'trfbles' 

LntV'^'r:,."""^'".'"'"";"'- ""'""•■""'"'  ''"■^""*'''  '""'  """t"'"-'!  .ton... -<Jlacler  .uovel 
nients.  -Glacier  im.d.-  Ice  toi.gueH  or  devir*  slkleH.  _  ited  »now.  -Surface  melting. 

Pioneer  Explorations  in  the  High  Sierra 

John  Mulr  -Jo«e,.h  Le  Conte.  -  Geological  Survey  of  California. -J.  U.  Whitney  - 
Clarence  King.  -  Coniiilions  favoring  obnervationi. 

Ancient  Glaciers  .... 


rAoa 

41 


40 


62 


CHAPTER   IV. 

Glaciehs  of  Northern  California  and  the  Cascade  Mountains  . 

Volcanoeg  of  the  Paclflc  coaat. 
Mount  Shasta 

Observations  by  Clarence  King.  -  Observations  by  Gilbert  Thompson. 
MoiNT  Rainier  (Tacoma) 

Glaciers  In  the  Unlte.l  States  first  reported  by  A.  V.  Kautz.  -  Observations  by  S   F 
hmmons.  — Uecent  fwcents.  ' 

Mount  Hood 

Observations  by  A.  Wootl.  -  Observations  by  Arnokl  Hague. 

Mount  Rakek 

•        .        . 

Observations  by  E.  T.  Colman,  J.  S.  Diller,  andJ.  S.  Newberry. 


66 
66 
62 

07 
69 


CHAPTER   V. 


Glaciers  op  Canada 


W^'s'lfrTn"'  m  ^°;'"»«'-'«- -«"*«'«"  "'  t>»e  Sel-irk  mountains.  -  Observations  by 
W.  S  Green.  -  Illecellewaet  glacier.  -  Glacier  of  the  Siiklne  Kiver  region.  -  Glaciers  of 
Northwestern  Canada  described  In  connection  with  those  of  Alaska. 


71 


CHAPTER    VI. 


Glaciers  of  Alaska 


Topographic  an.l  climatic  conditions  favoring  glaciation.  -  Height  of  Mount  Login  and 
ot  Mount  St.EIIa8.-Narrative8  of  early  voyages.  -  Belcher,  Vancouver,  and  otlfers- 

r^rZbTc^VHsr- "  "•  "*'-^-^'  ''■  «• "---«-  ---s- 

Tide-water  Glaciers 

Hutu  glacier.  —  Norris  glacier. 

Taku  Glacier      .        .        . 

**■•••.. 
Mum  Glacier      .        . 

Indian  names. -Muir's  exploration.  -  Observations  by  Trofessors  Wright  and  Reid  1 
Msit  by  the  present  writer.  -  Glacier  bay.  _  Thickness  of  the  Ice.  -  IcebergT  two 
hypotheses  concerning.  -  An  ancient  forest  beneath  the  ice.  -  Characteristlcs^f  tie 
glacier's  surface.  -  Dying  glacier.  -  Recent  recession.  -  Vancouver's  observa  on  on  he 
former  extent  of  glacial  ice  in  Glacier  bay.  o"»ervauon  on  tne 

Glaciers  on  the  West  Side  of  Glaciek  Bay 
Pacific  glacier.  —  Glacier  of  Dundas  bay. 


74 


77 

78 
80 


91 


Gt 


■i 
I 


PAGE 

41 

1. 

e- 

49 


66 
66 


.      67 


71 


CONTENTS.  VJI 

I'.VdK 

Glaciers  ok  Disenciuntment  Bat U2 

Turiii-r,  Hubbard,  and  Nuiiatak  glaciers.  —  View  from  Ua^^nke  iiland.  —  View  from 
Oaier  inhind.  —  Caiio  Enciiantiiient. 

Icy  Cai'k ".         .        .         .        .        .         .96 

AlI>INE    (il.ACIERA 90 

Vaiit  ik'vi'i  region  aUxit  Momiti!  Fiilrweatlier,  Lugaii,  aiid  Ht.  Eliai.  —  View  nortliward 
from  Mount  St.  Kliaa.  —  8eward  glacier. —ice  falls  and  rapids.  —  Agassi:^  glacier.— 
Uuyot  glacier. 

Olacikrs  of  Lynn  Canal 101 

Tnya  inlet.  —  Cl.ilkat  Inlet.  —  Davidson  glacier. 

Glaciekh  of  the  Interior 104 

(llncitTH  of  Chilkoot  and  C'hi'.kat  passes.  —  Observations  W>'  E.  T.  Olave. —Glaciers  be- 
tween Yukon  luul  topper  rivers.  —  Ubservatioi  of  C.  W.  lliiyes.  —  Fredrick  Schwntka.  — 
H.  T.  Allen. 

AbAENCE    of    (iLACIEKS    IN    CENTRAL    AND    NORTHERN    AlAHKA  ....       107 

Gla(  ii;iis  OK  THE  Alaskan  Peninsula  ano  the  .ileltian  I.'iLANiis  .         .        .     10b 
Mt.  Mukiishin. 

Piedmont  Glaciers •   .     100 

Characteristics.  —  Bering  glacier. 

Malaspina  Glacier 109 

Area.  —  Lobes.  —  Characteristics  of  the  uon-moralne-covered  surface.  —  Moraines.  —  Sur- 
face of  the  fringing  moraines.  —  Forests  on  the  moraines.  —  Character  of  the  outer  nuirgin. 

—  Icy  cape.  —  Sitkagi  bluifs.  —  Marginal  lakes.  —  Crater  lake.  —  Lake  'Jastani.  —  I.akes 
about  the  Clialx  hills.  —  Drainage.  —Fountain  stream.  —  Vahtse.  —  Osar,  Kame.nnd  Kiwik 
streams.  —  Sub-  and  englacial  deposits.  —  (Jsars.  —  Alluvial  cones.  —  (ilaclal  and  ocean 
records.  —  Kecent  advance  of  the  ice.  —  Fossil  shells  of  living  marine  species  at  high 
elevations. 

Subsoil  Ice     .         .         • 127 

Frozen  subsoil  along  the  Yukon.  —  Lieut.  CartwcU's  explorations  on  Kowak  river.  —  Ice 
cliffs  of  Kschscholtz  bay.  —  Remains  of  the  mammoth.  —  Character  and  origin  of  the 
tundra.  —  Deptli  of  frozen  subsoil  in  Siberia.  —  Explanations  of  the  origin  ()f  subsoil  ice. 

—  Computations  of  Prof.  K.  S.  Woodward.  —  A  possible  origin  of  frozen  subsoil. 


74 


CHAPTER   VII. 


77 

78 
80 


91 


Glaciers  in  the  Greenland  Region 

Grinnell  Land 

Observations  by  members  of  the  Lady  Franklin  Hay  expedition.  —  Report  by  Gen.  A.  W. 
Greely.  —  Henrietta  Nesndth  glacier.  —  Reports  by  Lieutenant  Lockwootl  and  Sergeant 
Brainard.  —  Mer  de  Glace  Agassiz.  —  "  Chinese  Waiy 

Greenland      

Extent  of  continental  glacier.  —  Character  of  the  interior.  —  Elevation  of  central  part  of 
the  ice  sheet.  —  Characteristics  of  the  margins  of  the  Inland  ice.  —  Observations  of  Lieu- 
tenant I'eary  near  Disco  island.  —  Hunil)oldt  glacier.  —  Observations  by  Dr.  Kane  on  the 
west  coast.  —  Observations  by  Dr.  Xansen  on  the  east  coast.  —  Reports  of  Lieutenant 
Lockwood  and  Sergeant  Brainard  concerning  glaciers  in  the  north  of  Greenland.  —  Cape 
Britannia.  —  ExploTations  of  the  interior.  —  Baron  Xordenskiold.  —  Lieutenant  Peary.  — 
Christian  Maigaara.  —  Dr.  Nansen.  —  Importance  of  the  study  of  Arctic  glaciers.  — 
Observations  by  Chamberlin. 


131 
131 


133 


vm 


CONTENTS. 


CHAl'TKU    VIII. 

PAOE 

Climatic  Changes  iNUiCATKi)  in   tiik  (;i.a.  ikiis  ok  Nohiii  AMEmtA        .         .        .140 
(;i.«ra.-t.T  <.f  tlu<  ..vl.l,.„,.,.._u.,v,r,lH  of  n-oei.t  reocMloii  In  tlio  glacleri  of  (•Hllfornla. 
Or^-go...  an.l  WiuihlnKt..,,.    -  HrltlM.  (oh.mblfi.  -  .\la«ka.  -  <lr..ei.l«n.l.  -  W.-IkIu  ..f  the 
evl.lence.-CUiiiatle  ol.aiitft'H  iiHllcHt.Mi  l>y  H,..  glaficrn  of  the  NorthtTii  llfiiii»i.lierv . 
THE«>HETI(  AI.    C'ONSIUEHATIONS ,rQ 

Influence  of  dt'brls  on  the  ««lvBn<'.-  and  retreat  of  glaciers.  * 


CHAPTEH    IX. 

How    AND    VVllV    Gt.A(  IEI18    MoVK     . 

•  •  •  .  . 

The  nature  of  glueial  Mow.  —  (Jl)8erv;.tlons  by  Koch  and  Ktocke. 

IIVI'OTHEHEH    OK    (il.ACIAI,    MoTION 

The  «1I.11„K  hypothenlH.  _  '•  In,  SauMure'B  theory."  -  The  hypothesis  of  .Ulatatlon.-  The 
hypothesm  o  pla«tl.-lty. -The  hypotlu-Kin  of  r-Melation.  -  The  hypotheniH  of  expannlon 
an.  eontiuetlo..._The  hypothe«m  of  Ihiuefaction  un.ler  prtxHure. -  T!...  hypothesis  of 
molecular  change. -The  hypothesis  of  granular  change.  -  Observations  l.yT.  V.  Cham- 


An  Eclectic  Hvpothesis 

Summary  of  the  properties  of  lee. 
eclectic  hypothesis. 


■  Sunnnary  of  glacial  »>henoniena.  —  Authors  ot  the 


100 


103 


186 


CHAPTER    X. 


The  LirE  History  of  a  Glacieu 


Periods  of  growth  and  decline.  -  The  ano«-  line.  -  Spheroid  of  32«.  -  Birth  of  a  glacier  - 
i)evelopM.ent.  -  Moraines.  -  Marginal  lakes.  -  Ice  casca.les.  -  Widening  and  tlattening  of 
moraines.-  Buried  forests.  -  Forest-covered  moraines.  -  Debris  pyramids.  -  Stran.led 
lateral  moraines.  -  Polished  and  striated  surfaces.  -  Terminal  nu.raines.  -  .Moralne- 
damme.1  lakes.  -  Kock-basin  lakes.  -  l>eath  of  a  glacier.  -  Climatic  cycles.  -  Pleistocene 
Ice  sheets. 


Concluding  Note 
Index 


190 


.     206 
.     207 


W 


l-AOK 
.       1-IU 


.     160 


ili.u8tratio:n^s. 


-aoJOJoo- 


100 


103 


186 


.     100 


206 
207 


P.,ATK 

1. 

it 

2. 

it 

3. 

it 

4. 

tl 

5. 

4( 

0. 

it 

7. 

H 

8. 

tt 


it 
(I 


SKETcir  Mai-  of  North  AMEiiifA 

Fi<i.   A.  —  MoivT  Dana  Gi-a(  ieu,  Cai.ifoknia 


10. 

11. 
12. 


•'  13. 

"  14. 

♦•  16. 

-'  10. 


PAflK 

Frontispiece 

NA    Gl-A(  IEU,    CaMFOKNIa      ) 

Fk;.  H.  —  M,„NT  LvELL  Glacieh,  Calikohnia  ) ^ 

MoiNT  Lyei,l,  Camkohnia 

MoiiAiNAL  Kmhankmenth,  Bu)of)v  CaSon,  Califok.ma 

Sketi  II  Mai-  of  Moint  Shasta,  Camfoiima 

F„j.  A.  — Whitney  Glacieh,  Moi:nt  Shasta,  Camfohnia, 

Fkj.  JJ.  — Summit  or  Moi;.nt  I{aime«,  WAsiiiNoroji 

Sketch  Map  of  Mount  Kainiek 

Fio.  A.  — Surface  of  Cowmtz  Glacieh,  Mount  Rainieh 
.Fig.  B.  —  Ice  Cave  at  the  Eni.  i     Nisijuallv  Glacieu,  Mount  Raimei.: 
(Fig.  a. —  Summit  of  Mount  Baker,  Washington 
|Fig.  B.  —  Cuevasses,  Illeceli.ewaet  Glaciek,  Canada 

jFlO.  A.  —  iLLECELLEWAEl   Gl.ACIKIt,  SELKIRK  MOUNTAINS,   CaNADA  i 

/Fuj.  B.  —  Side  View  of  Illecellewaet  Glacier  J 

NoRRis  Glacier,  Taku  Inlet,  Alaska 

Map  of  Muir  Glacier,  Alaska 

(Fig.  a.  — Ice  Cliff  at  thk  End  of  Muih  Glacier   ) 

(Fig.  B.  — Ice  Cliff  OF  Muir  Glacier  AT  Low  Tide) 

jFio.  A.  -Surface  of  Mum  Glacier,  with  White  Glacier,  a  Tributary, 

(Fig.  B.  —Buried  Forest  at  the  End  of  Muir  Glacier 


17. 
18. 
19. 
^0. 

21. 

22 


(Fig.  A.  — HuDRARD  Glacier,  Disenchantment  Bay,  Alaska) 
I  Fig.  B.  —Glaciated  Rocks,  Haenkb  Island,  Alaska  { 

(Fig.  a.  — Surface  of  Seward  Glacier,  Alaska 
{Fig.  B.  — Davidson  Glacier,  Lynn  Canal,  Alaska 
Sketch  Map  of  Mount  St.  Elias  Region,  Alaska 
Front  of  Malaspina  Glacier,  Alaska 
Central  Portion  of  Malaspina  Glacier,  Alaska 
Malaspina  Glacier,  from  the  Chaix  Hills       .        .         .         . 
(Fig.  A.  — Moraine-covered  Border  of  Malaspina  Glacier) 
/Fig.  B.  — Entrance  to  Tunnel  in  Malaspina  Glacier  J 

(Fig.  a. —Bryant  Glacier,  Greenland 
|Fio.  B.  —  Tuktoo  Glacier,  Greenland 


42 
62 
66 

62 

04 
(iO 

08 

72 

78 
80 


.  84 
88 
!»4 

100 

108 
110 
112 
118 

124 
142 


X  ILLUSTRATIONS. 

PAOB 

FionnE  1.   Ideal  Sketch  Map  of  an  Alpine  Glacier 7 

"       2    Drllilin _  25 

"       3.  Glacier  Tables,  Parker  Creek  Glacier,  California         .        .        .        44 

"       4.    Ice  Pyramids,  Mount  I  yell  Glacier,  California 45 

"       6.    Iceberg,  MuiR  Inlet,  Alaska .83 

"       0.  Section  OF  THE  End  OF  A  Tide -WATER  Glacier.     (After  Keid.)        .        .     85 

7.  Section  OF  THE  End  OF  A  Tide -WATER  Glacier^    (After  Russell.)        .        86 

8.  Side  View  of  a  Medial  Moraine  on  Muir  Glacier,  Alaska         .        .     88 

"       9.   Lakelet  on  Malaspina  Glacier,  Alaska 116 

"      10.    Grain  of  Glacial  Ice '      ^        ^  I75 


I  am  especially  indebted  to  the  Director  of  the  U.S.  Geolofrical  Survey  for  the  electro- 
types used  in  reproducing  the  illustrationa  forming  Plates  3,  4,  6,  1 7,  18,  19,  and  20.  Other 
acknowledgments  for  sim'lar  favors  will  he  made  m  advance 

I.  C.  R. 


GLACIERS    OF   NORTH    AMERICA. 


o>tioo- 


CHAPTER   I. 


INTRODUCTION. 

It  iriay  be  said  of  glaciei-s  in  general  that,  Lhey  are  bodies  of  ice  formed 
by  the  accumulation  and  consolidation  of  snow  in  regions  where  the 
snowfall  for  a  series  of  yeai-s  is  in  excess  of  the  amount  melted  and  that 
they  flow  to  regions  where  waste  exceeds  supply. 

While  a  typical  glacier  is  easily  recognized,  and  there  is  no  dissent 
from  what  is  commonly  undei-stood  by  the  name  applied  to  bodies  of  flow- 
ing ice,  yet  the  limitations  of  the  term  are  indefinite.  A  type  may  be 
chosen,  as  the  well-known  Mer  de  Glace,  Switzerland,  for  exam{)le,  in 
which  most  of  the  characteristics  of  glaciei-s  are  exhibited.  Other  ice 
bodies  are  known,  however,  equally  deserving  to  be  classed  as  glaciers, 
that  are  markedly  different  from  such  a  typco  The  vast  ice  sheet  of 
Greenland  exhibits  a  great  departure  from  the  ice  streams  of  Switzerland 
in  certain  features  ;  while  the  small  ice  bodies  in  the  Sierra  Nevada, 
California,  present  minor  vacations  in  other  characteristics.  In  both  of 
these  illustrations,  and  in  many  others  equally  at  variance  with  the  type 
chosen,  the  term  glacier  is  as  appropriate  as  in  the  case  of  the  ice  stream 
on  the  border  oi  the  Vale  of  Chamounix. 

The  difficulties  in  determining  the  limitations  of  the  term  glacier  may 
be  illustrated  by  the  use  of  the  word  river.  When  does  a  stream  cease  to 
be  a  brook,  or  a  creek,  or  even  a  lake,  since  many  lakes  are  but  ♦expan- 
sions of  streams,  and  reach  the  dignity  of  a  river?  In  a  similar  way,  it 
is  difficult  to  decide  when  an  accumulation  of  snow  acquires  sufficient  of 
the  characteristics  of  a  typical  glacier  to  be  included  in  the  same  class  ; 
or  again,  when  a  glacier  loses  motion  and  becomes  a  stagnant  ice  body, 
when  it  shall  ce?^se  to  be  known  by  tiie  title  it  ea'-ned  when  it  was  au 
avenue  of  ice  drainage. 


GLACIERS    OF    NOIiTH    AMKKICA. 


In  instances  where  the  conditions  are  indefinite  or  peculiar,  only  an 
arbitrary  decision  can,  perhaps,  be  reached  ;  but  usually  the  presence  or 
absence  of  a  number  of  the  commonly  recognized  characteristics  of  typi- 
cal glaciers  is  sutlicientiy  pronounced  to  exclude  controversy. 


I 


11' 


Leading  Characteuistics  of  Glaciers. 

Mode  of  Accumulation.  —  The  formation  of  glaciers  in  any  region 
depends  primarily  on  climatic  conditions.  When  the  climate  is  such  that 
the  amount  of  snow  falling  for  a  term  of  years  is  in  excess  of  the  amount 
melted,  evaporated,  or  blown  away,  perennial  snow  banks  are  formed,  the 
more  deeply  buried  portions  of  whir  a  become  compacted  into  ice.  The 
change  i.om  snow  to  ice  is  known  to  r3sult  from  pressure  and  from  par- 
tial melting  and  refreezing.  Many  observations  have  been  made  which 
show  that  normal  glaciers  liave  a  characteristic  flowing  motion.  The 
material  of  which  they  are  composed  is  drained  from  regions  of 
accumulation  in  much  the  same  manner  as  rivers  drain  areas  where 
the  rainfall  exceeds  evaporation.  This  process  of  ice  drainage  relieves 
areas  of  heavy  snowfall  from  their  burdens,  and  prevents  indefinite 
accumulation. 

Three  Tj'pes  of  Glaciers.  —  For  convenience  of  reference  the  glaciers 
nov/^  known  may  be  arranged  in  three  classes,  namel}',  alpine,  piedmont^ 
and  continental.  These  three  classes  are  not  always  distinct  and  clearly 
sejjarable,  but  typical  examples  of  each  may  be  selected  that  are  well 
characterized,  and  dilfer  in  essential  features  from  typical  examples  of  each 
of  the  other  classes.  In  each  group  there  are  conspicuous  variations 
which  suggest  minor  or  more  specific  subdivisions. 

Of  the  three  great  classes  referred  to  above,  the  most  widely  known  is 
the  alpine  type,  which  derives  its  name  from  the  mountains  of  central 
Europe,  where  it  was  first  studied.  Alpine  glaciera  occur  about  high 
peaks  and  on  the  summits  and  flanks  of  mountain  ranges  in  many  parts 
of  the  world,  but  reach  their  most  perfect  development  in  tempernte 
regions.  The  Himalayas,  the  Alps,  the  mountains  of  Scandinavia,  the 
Southern  Alps  of  New  Zealand,  the  Cordilleras,  etc.,  furnish  well-known 
examples.  Glaciere  of  this  type  originate  as  a  rule  in  am[)hitheatres  and 
cirques,  partially  surrounded  by  lofty  peaks  and  oversiiadowing  preci- 
pices, and  flow  through  rugged  valleys  leading  from  them  as  winding 
ice  rivers  which  carry  the  excess  of  snow  falling  on  the  mountains  to 


INTUODUCTION. 


lower  regions,  where  a  higher  mean  annual  temperature  causes  it  to  melt. 
They  are  essentially  streams  of  ice,  formed  usually  by  the  union  of  many 
branches,  and  end  aljruptly  when  the  drainage  changes  from  a  solid  to  a 
liquid  form. 

(ilaciers  of  the  piedmont  type  are  formed  where  alpine  glaciers  leave 
the  rugged  defiles  through  which  they  flow  and  expand  and  unite  on  an 
adjacent  plain.  They  may  be  considered  as  analogous  to  lakes,  for  the 
reason  that  they  are  fed  by  tributary  ice  streams.  The  influx  of  ice  is 
counterbalanced  by  melting,  especially  from  the  surface  and  borders  of 
the  partially  stagnani  mass.  The  chai-acteristics  of  glaciers  of  this  type 
are  foreshadowed  when  individual  alpine  glaciera  leave  a  high-grade  gorge 
and  expanil  in  a  lateral  valley  or  on  a  plain.  The  expanded  terminus  of 
Davidson  glacier,  on  the  border  of  Lynn  canal,  Alaska,  illustrates  what 
may  be  take,  as  the  first  step  toward  the  formation  of  a  piedmont  glacier. 
The  semicircular  or  delta-like  ice  foot  of  the  Rhone  glacier,  Switzeiland, 
v/here  it  spreads  out  at  the  head  of  the  Rhone  valley,  is  a  more  widely 
known,  although  a  comparatively  diminutive  example  of  the  same  char- 
acter. If  one  fancies  a  score  or  more  glaciei-s  of  the  Davidson  and  Rhone 
type,  uniting  on  a  plain  and  forming  a  single  confluent  plateau  of  ice 
many  square  miles  in  area,  he  will  appreciate  the  leading  characteristics 
of  tlie  ice  sheets  termed  piedmont  glaciers. 

A  type  of  the  piedmont  glacier,  and  the  only  one  of  the  class  thus  far 
described,  is  Malaspina  glacier,  Alaska,  situated  at  the  southern  base  of 
Mount  St.  Elias  and  neighboring  mountains,  from  which  it  is  nourished 
by  many  ice  streams.  This  magnificent  ice  sheet  covers  an  area  of  1500 
square  miles,  and  is  from  1000  to  1500  feet  thick.  West  of  Malaspina 
glacier,  and  occupying  a  plain  intervening  between  high  mountains 
and  the  sea,  is  another  piedmont  glacier,  knovai  as  Bering  glacier, 
which  is  of  the  same  general  character  as  its  companion,  but  has  not 
been  explored. 

Ice  bodies  of  the  third  class,  as  their  name  implies,  are  of  vast  extent 
and  may  even  cover  entire  continent'^.  Existing  examples  are  confined 
to  Greenland  and  to  Antarcti'  regions.  Others  that  have  now  vanished, 
left  unmistakable  records  over  large  portions  of  northeastern  North 
America  and  northwestern  Euroije.  The  principal  characteristics  of  con- 
tinental glaciers  are  their  vast  extent,  their  comparatively  level  surfaces, 
and  the  prolongation  of  portions  of  tb.eir  Iwrdei's  into  lol>es  and  even 
into  well-defined  streams,  where  the  topographic  and  other  conditions  are 
favorable. 


4  GLACIEHS   OF    NOKTH    AMERICA. 

On  comparing  the  three  classes  of  glaciers  just  enumerated,  one  finds 
that  alpine  glaciers,  when  well  developed,  appear  as  trunk  streams  formed 
by  the  union  of  many  branches.  ^  They  usually  flow  through  narrow 
valleys  froii  higher  to  lower  regions,  and  end  abruptly  in  precipitous 
walls  of  ice  or  expand  at  their  extremities  and  terminate  with  low  frontal 
slopes,  according  to  local  conditions.  In  many  ways  they  are  analogous 
to  rivers.  Piedmont  glaciers  receive  many  tributaries  of  the  alpine 
type,  are  not  confined  by  rocky  walls,  and  do  not  have  the  well-defined 
stream-like  flow  exhibited  by  glaciers  descending  narrow  valleys.  Tney 
are  only  moderately  lobed,  do  not  send  out  well-defined  branches,  and  are 
in  part  stagnant, ice  masses.  Their  nearest  counterparts  in  ordinary  water 
drainage,  as  already  mentioned,  are  found  in  lakes  fed  by  mountain 
streams.  Continental  glaciers  are  without  tributaries,  their  broad  surfaces 
forming  the  necessary  gathering-ground  for  snov/  accumulation.  Their 
margins  may  be  strongly  lobed,  or  even  send  out  well-defined  tongues  of 
ice,  but  the  area  of  ice  extending  beyond  the  margins  of  the  central  snow 
field  is  in  existing  examples  comparatively  small. 

Each  of  the  three  types  of  glaciers  here  enumerated  is  represented  in 
North  America,  and  their  characteristics  and  distribution  will  be  described 
in  the  following  chapters. 


N6v6  and  Glacier  Proper.  —  Glaciers  of  the  alpine  type,  and  in  a 
less  marked  way  those  of  the  continental  type,  have  their  surfaces 
divided  into  two  portions,  a  nev6  or  snow  region  above,  and  an  ice  portion 
below.  The  lower  portion  has  no  specific  name,  but  is  frequently  desig- 
nated as  the  "glacier  proper.  "  The  line  of  demarcation  is  the  snotv  line, 
i.e.  the  lowest  limit  of  perennial  snow.  As  compacted  ice  occurs  also 
directly  beneath  the  n^v^  from  which  it  is  formed,  this  division  of  a 
glacier  into  two  portions  applies  only  to  the  surface.  Moreover,  the 
position  of  the  dividing  line  is  subject  to  secular  variations.  At  times, 
possibly  for  many  consecutive  years,  in  the  case  of  small  glaciei-s,  the 
snow  may  completely  cover  the  true  ice,  so  that  one  might  Avalk  over  the 
accumulation  and  easily  mistake  it  for  the  snows  of  a  single  winter,  and 
be  led  to  conclude  that  it  was  not  entitled  to  be  considered  as  a  member 
of  the  great  family  of  glaciei's. 

The  n4iv6  is  composed  of  str.atified  granular  snow  which  is  white  or 
grayish  white  in  color.  The  snow  on  high  mountains  is  apt  to  be  exceed- 
ingly fine,  light,  and  dry  when  first  formed  ;  but  by  partial  melting  and 
ref reccing  it  acquires  a  coarae,  granular  texture,  much  like  compacted  hail, 


INTRODUCTION. 


and  also  becomes  consolidated  and  hard.  The  surface  of  the  n6y6  is  many 
times  so  softened  l)y  the  warmth  between  summer  storms,  that  a  thin  crust 
of  ice  is  formed  when  the  temperat'ne  is  again  lowered.  1'his  crust  is 
buried  beneatli  the  next  succeeding  snowfall  and  remains  in  the  growing 
deposit  as  a  thin  stratum  of  ice.  Ndves  are  almost  entirely  free  from 
stones  or  dirt,  although  even  on  the  highest  mountains,  the  dust  borne 
from  naked  cliffs  is  widely  spread  over  their  surfaces  and  diminishes  their 
brilliancy.  This  general  dust-covering  is  frequently  not  noticeable  until 
some  really  clean  snow  surface  is  brought  in  contrast  with  it.  Whcit  u  lake 
on  the  n6y6  is  drained  and  leaves  a  fresh  surface  of  dazzling  whiteness,  the 
surrounding  area  frequently  shows  a  gray  tint  by  contrast,  thus  revealing 
tlie  presence  of  dust  which  has  been  sprinkled  over  it.  Sometimes  thv. 
covering  of  dust,  especially  on  the  lower  portions  of  the  n(;v(is  of  alpine 
glaciers,  is  sufficiently  pronounced  to  form  a  definite  division  plane  when 
buried  by  subsequent  snoAvfalls.  Illustrations  of  such  an  occurrence  may 
frecpiently  be  seen  in  the  walls  of  fissures.  In  the  great  open  fissures  or 
crevasses  that  bre'^-k  the  ndv^s  in  the  region  about  Mount  St.  Elias,  a 
dozen  more  or  less  distinct  strata  separated  by  bands  of  blue  ice,  a  fraction 
of  an  inch  thick,  or  by  still  more  conspicuous  dust-stained  layers,  may  be 
frequently  counted.  In  some  instances  the  layei-s  of  granular  snow  are 
fully  fifty  leet  thick,  even  after  having  passed  from  the  light,  mealy 
consistency  of  freshly  fallen  snow  to  the  much  more  compact  condition 
of  the  granular  n<?v6  snow,  thus  indicating  the  abundance  of  the  snow- 
fall in  the  regions  where  glaciers  have  their  birth.  The  surfaces  of 
n6\6s  are  renewed  many  times  during  the  year  by  fresh  snow.  Stones 
and  dirt  falling  on  them  from  surrounding  cliffs,  or  swept  down  by 
avalanches  from  tributary  slopes,  are  buried  from  sight  and  enclosed  in 
the  growing  deposits. 

Below  the  snow  line,  the  true  glacier,  composed  of  compact  ice,  makes 
its  appearance  at  the  surface.  The  horizontal  stratification  so  well  marked 
in  the  n^v^  is  nearly  or  quite  obliterated,  but  the  ice  takes  on  a  character- 
istic bant'ed  structure,  due  to  alternation  of  thin  sheets  of  clear,  blue  ice 
with  sheets  of  vesicular,  white  ice.  As  has  been  shown  by  laboratory 
experiments  as  well  as  observations  on  glaciers  themselves,  this  peculiar 
banded  or  ribboned  structure  is  caused,  in  part  at  least,  by  pressure,  and  is 
analogous  to  the  slaty  cleavage  observable  in  certain  rocks.  At  the  lower 
extremities  of  glaciers  in  many  instances  the  banded  structure  is  obscure, 
or  ijerhaps  entirely  obliterated,  and  the  ice  presents  a  coarse,  granular 
appearance  not  unlike   the    grain  oi   crystallized  marble.      As    will    be 


6 


GLACIERS   OF   NORTH    AMERICA. 


explained,  this  "  glacier  grain "  is  not  confined  to  the  extremities  of 
glaciei-s,  but  has  been  recognized  throughout  the  extent  of  the  glaciers 
proper. 

The  ice  below  the  snow  line  is  frequently  dirt-stained  and  more  or  less 
completely  covered  with  angular  stones  and  large  jock  masses.  This 
superficial  covering  is  so  general  on  many  glaciers  that  from  a  distance  no 
traces  of  ice  can  be  seen,  and  they  appear  as  dark  and  barren  as  a  newly 
plowed  field.  In  a  general  view  of  a  snow-covered  mountain  range  the 
two  surface  divisions  of  the  glaciers  on  its  sides  are  usually  distinctly 
shown  by  coutnist  in  color.  The  higher  or  neve  portions  are  white  and 
glistening,  while  the  lo'ver  portions  either  reveal  the  blue  tint  of  compact 
ice  or  are  dark  with  earth  and  stones. 

The  debris  that  falls  on  a  neve  from  bordering  cliffs,  and  the  dust  blown 
over  its  surface,  sink  into  the  soft  snow,  principally  on  account  of  the 
absorption  of  heat  owing  to  their  dark  color,  and  are  buried  by  later  snow 
storms.  As  the  neve  becomes  consolidated  and  acquires  motion,  this 
debris  is  carried  along  within  its  mass.  In  the  region  below  the  snow- 
line, however,  where  the  annual  melting  exceeds  the  annual  snowfall, 
the  surface  of  the  ice  is  liquefied,  and  foreign  substances  previously  buried 
become  concentrated  at  the  surface.  The  tendency  of  the  neve  is  to  bury 
foreign  objects,  and  of  the  glacier  proper  to  concentrate  them  at  the 
surface.  For  this  reason  the  lower  and  consequently  the  more  wasted 
portion  of  a  glacier  is  the  more  thoroughly  dirt-covered. 


"fi: 


Moraines.  —  All  of  the  debris  carried  by  glaciers  may  be  designated 
in  general  as  morainal  material.  When  arranged  in  certain  more  or  less 
definite  ways  it  is  known  under  specific  names.  When  distributed  along 
either  margin  of  a  glacier  it  forms  lateral  moraines.  When  two  glaciers 
unite,  the  right  lateral  moraine  of  one  of  the  branches  joins  the  left  lateral 
moraine  of  its  companion,  thus  forming  a  medial  moraine  in  the  central 
portion  of  the  compound  glacier  below  the  junction.  When  a  trunk 
glacier  is  formed  by  the  union  of  several  branches,  as  is  frequently  the 
case,  the  number  of  parallel  lines  of  debris  on  its  surface  is  correspond- 
ingly increased,  being  always  one  less  than  the  number  of  well-defined 
branches  that  unite  to  form  the  compound  stream.  This  nomenclature 
will  be  better  understood  by  referring  to  the  following  ideal  sketch  map 
of  the  surface  of  an  alpine  glacier,  formed  by  the  union  of  four  tribu- 
taries. The  moraines  on  the  surface  of  the  ice  are  shown  by  dots  and 
the  mountain  slopes  by  sketch  contours. 


INTKODUCTION. 


The  debris  carried  to  the  end  of  the  glacier  and  deposited  about  its 
extremity,  in  some  cases  forms  a  crescent-shaped  ndge,  known  as  a 
terminal  moraine.  Simihir  moraines  about  the  margin  of  piedmont  and 
continental  glaciers  are  usually  designated  as  frontal  moraines;  when  two 


Pig.  1.  — Ideal  sketch  Map  of  an  Alpink  Olaciee,  showing  Lateral,  Medial, 

AND  TEUMINAL  MoHAINES. 

I  lobes  on  tbe  outer  margin  of  such  glaciers  unite,  the  debris  deposited 
lalong  the  i.  le  of  junction  forms  interlobate  moraines.  Moraines  are 
isubglacial,  englacial,  or  superglacial  according  to  their  position. 

Other  somewhat  technical  terms  used  to  designate  various   modifi- 
[cations  of   morainal   deposit  will   be   explained   in   treating   of  glacial 
records. 


Crevasses.  —  Moving  ice  masses,  especially  when  flowing  over  rough 

Surfaces  or  through  rugged  valleys,  are  subjected  to  stresses  which  cause 

(them  to  break  and  fissures  to  open.      Such  open  fissures  were  termed 

revasses  by  Swiss  mountaineers,  long  before  the  attention  of  scientific 

len  had  been  called  to  them.     The  name  has  been  adopted  by  glacialists 

a  general  term  for  the  gaping  fissures  that  so  frequently  break  the 


8 


GLACIEU8   OF   NOKTH    AMEKICA. 


surfaces  of  moving  ice  masses.  Crevasses  occur  both  in  n6v^s  and  in 
true  glacial  ice,  and  present  varying  characteristics  which  have  led  to  a 
somewhat  specific  classification. 

The  snow  fields  at  the  heads  of  alpine  glaciers  are  frequently 
traveled  by  fissures  several  hundred  feut  long  and  varying  in  width 
up  to  50  feet  or  more.  They  are  widest  in  the  central  [)()rtion,  and 
taper  gradually  to  mere  cracks  at  their  extremities,  wliich  are  frequently 
curved  in  opposite  directions.  Even  the  greatest  crevasses  are  at  first 
simple  or  compound  fractures,  too  narrow  to  allow  one  to  insert  the 
thinnest  knife  blade,  and  slowly  open  in  the  course  of  weeks  or  months. 
This  widening  of  crevasses,  especially  in  neves,  is  due  to  the  stretching 
of  the  material  that  they  travei'se.  It  is  frequently  stated  that  ice, 
though  jjlastic  under  pressure,  yields  to  tension  only  by  rupture.  The 
slow  o[)ening  of  crevasses  by  the  widening  of  their  central  portions, 
certainlv  indicates,  however,  that  ice,  when  subjected  to  slowly  acting 
tension,  does  stretch  to  some  extent  without  fracture. 

As  stated  above,  crevasses  begin  as  narrow  cracks  and  gradually  widen. 
While  camping  on  the  broad  neves  in  the  Mount  St.  Elias  region,  my 
attention  was  frequently  called  to  the  formation  of  these  breaks  in  the 
ice.  On  one  occasion,  while  sleeping  in  a  tent  far  out  on  the  neve  of  the 
Agassiz  glacier,  I  was  wakened  several  times  during  the  night  by  rum- 
bling sounds  accomjjanied  by  sharp  crashes,  which  seemed  to  proceed 
from  the  ice  immediately  beneath  our  tents.  With  each  crash  the  ice 
trembled  and  vibrated  as  if  an  earthquake  wave  had  passed  through  it. 
The  sounds  came  so  suddenly  and  were  so  startling  that  some  of  my 
party  who  were  not  familiar  with  the  behavior  of  glaciers,  rushed  from 
the  tent  in  considerable  alarm,  fearing  that  a  crevasse  was  about  to  yawn 
beneath  them.  In  the  morning  we  found  that  a  crack  in  the  ice,  several 
rods  in  length  but  without  appreciable  width,  had  formed  immediately 
in  front  of  our  tents. 

The  walls  of  crevasses  in  n^ve  regions  are  of  the  most  exquisite 
turquoise  blue,  the  color  deepening  below  the  surface  until  it  seems 
almost  black.  The  only  color  in  nature  that  rivals  the  blue  of  glacial  ice. 
is  seen  ^vhen  one  looks  down  into  the  unfathomable  sea.  The  sides  of 
crevasses  are  frequently  hung  with  icicles,  forming  rank  on  rank  of 
glittering  pendants,  and  fretted  and  embossed  in  the  most  beautiful 
manner  with  snow  wreaths,  and  partially  roofed  with  curtain-like  cornices 
of  snow.  These  details  are  wrought  in  silvery  white,  or  in  innumerable 
shades  of  blue  with  suggestions  of  emerald  tints.     When  the  sunlight 


INTHODUCTION. 


9 


s  and  in 
led  to  a 

■equently 
in  width 
tion,  and 
tequently 
e  at  tirst 
nsert  the 
r  months, 
itretching 

that    ice, 
ire.     The 

portions, 
/ly  acting 

lly  widen, 
■egion,  my 
iks  in  the 
eve  of  the 
t  by  rum- 
D  proceed 
h  the  ice 
hrough  it. 
me  of  my 
ished  from 
it  to  yawn 
ce,  several 
imediately 


■m 


enters  the  great  chasms,  their  walls  seem  encrusted  with  iridescent 
jewels.  The  still  watei-s  with  which  many  of  the  gulfs  are  partially  tilled, 
rertect  every  detail  of  their  crystal  walls  and  make  their  depth  seem 
infinite.  No  dream  of  fairy  caverns  ever  exceeded  the  beauty  of  these 
mysterious  crypts  of  the  vast  cathedral-like  amphitheatres  of  the  silent 
mountfiins. 

Encircling  the  upper  bordei-s  of  the  nev6  in  most  snow-filled  amphi- 
theatres, there  is  a  great  crevasse  or  a  series  of  nearly  parallel  and 
intersecting  fractures  that  differ  in  certain  ways  from  the  crevasses  formed 
lower  down.  The  most  rapid  motion  in  a  n^ve  probably  occurs  deep 
below  the  surface,  where  the  p  ;ssure  is  greatest  and  the  ice  compact.  The 
light  snow  forming  the  surface  of  the  nev6  is  carried  bodily  forward  by 
the  flow  of  the  ice  on  which  it  rests ;  this  together  with  the  general  settling 
of  the  newer  and  more  incoherent  snow  causes  it  to  break  away  from  the 
f:urrounding  cliffs,  (ireat  open  fissures  are  thus  formed,  which  border  the 
upper  margin  of  the  n^ve  and  separate  it  from  the  rocks  above  in 
such  a  manner,  in  many  instances,  as  to  offer  an  impassable  obstacle. 
These  breaks  frequently  mark  the  boundary  between  snow  work  and 
rock-climbing,  and  are  known  as  heiyschnimh,  or  mountain  crevasses. 
Break .  of  this  character  are  among  the  very  first  to  form  when  an  amphi- 
theatre becomes  snow-filled,  and  continue  to  appear  at  the  same  localities 
as  the  glacier  advances  in  age.  They  occur  close  to  the  bordering  cliffs 
but  leave  portions  of  the  neve,  frequently  several  rods  broad,  still  clinging 
to  the  rocks.  A  bergschrund,  in  the  majority  of  instances,  is  of  the  nature 
of  a  fault.  The  snow  left  attached  to  the  rocks  and  forming  the  upper 
margin  of  the  crevasse  stands  higher  than  the  opposite  margin  of  the 
fracture.  The  snow  forming  the  thrown  block,  has  been  affected  by  a 
downward  movement,  and  also  by  a  horizontal  movement  which  opened 
the  fracture.  In  observed  instances,  the  vertical  displacement  is  from  a 
few  inches  to  fifty  or  sixty  feet  or  more  ;  and  the  horizontal  movement 
shown  by  the  breadth  of  the  crevasse,  frequently  from  fifty  to  seventy-five 
feet.  At  times  compound,  or  step  faults,  as  a  geologist  would  call  them, 
are  formed  and  two  or  more  nearly  parallel  crevasses  break  the  surface. 
In  winter  these  breaks  are  filled  and  a  new  layer  is  added  to  the  surface 
of  the  ,n6ve,  but  during  the  succeeding  spring  they  form  again  in  about 
the  same  position  as  the  year  previous. 

In  the  breaks  encircling  the  head  of  a  neve,  the  rock  beneath  the  snow 
left  clinging  to  the  mountain  is  usually  exposed  and  becomes  greatly 
shattered  by  frost  and  changes  of  temperature.     The  blocks  thus  loosened 


10 


GLACIERS    OF   NORTH    AMERICA. 


are  plucked  oft  the  succeeding  year,  when  another  crevasse  forms  in  the 
same  locality.  It  is  thought  by  some  students  of  topography  that  the 
waste  from  these  exposed  surfaces  leads  to  the  growth  of  amphitheatres 
and  cirques  and  explains  many  of  the  peculiarities  in  the  relief  of 
glaciated  mountains. 

When  a  glacier  descends  a  precipice  it  may  become  broken  find  fall  in 
detached  blocks,  thus  forming  veritsible  ice  cascades;  but  the  fragments 
unite  again  at  the  base  of  the  cliffs  and  become  reconsolidatcd,  and  the  ice 
flows  on  as  a  continuous  stream.  At  other  times  the  descent  is  completely 
covered  with  ice  so  shattered  as  to  be  impassable,  and  presents  all  degrees 
of  diversity  between  ice  cascades  and  ice  rapids.  The  places  of  steep 
descent  in  the  floor  of  a  n^ve  frequently  lead  to  the  breaking  of  the  snow 
and  ice  into  cubical  blocks  of  all  dimensions  up  to  hundreds  of  feet  in 
diameter,  which  bear  a  striking  rese  mblance  to  towers  and  other  architec- 
tural forms,  and  add  most  attractive  features  to  the  scenery  of  glacier- 
covered  regions.  During  night  marches  on  the  glaciers  of  Alaska,  the 
writer  could  scarcely  put  aside  the  idea  that  these  shadowy  forms  par- 
tially illuminated  by  the  r|orthern  twilight,  were  in  reality  the  ruins  of 
marble  temples.  In  the  lower  portions  of  glaciers,  where  the  ice  is  more 
solid  and  where  surface  melting  is  more  rapid,  the  steep  descents  are 
marked  by  spires  and  pinnacles  having  extremely  rugged  and  angular 
forms,  separated  by  profound  crevasses.  These  true  ice  falls  are  much 
more  rugged  and  much  more  difficult  to  traverse  than  similar  descents 
in  the  n6v6,  and  are  seldom  accessible  even  to  the  most  experienced 
mountain  climbers. 

When  a  glacier  passes  over  a  moderate  inequality  in  its  bed,  it  is 
fractured  so  as  to  form  crescent-shaped  fissures  which  are  widest  just 
below  the  obstruction  and  gradually  close  as  the  slowly  moving  stream 
flows  on.  In  pas^nng  over  such  obstructions  the  surface  of  a  glacier, 
especially  in  the  n6v6  region,  sometimes  rises  so  as  to  have  a  buekward 
slope.  Instances  of  this  nature  have  been  observed  in  the  neighborhood 
of  Mount  St.  Elias.  Marginal  crevasses  are  formed  on  the  sides  of  well- 
defined  glaciers,  owing  to  the  friction  on  the  sides  and  the  more  rapid 
flow  of  the  central  portion.  These  breaks  trend  up  stream  at  angles  of 
approximately  40°,  and  are  broadest  at  the  shore.  When  the  banks  of  an 
ice  stream  are  of  snow  and  ice,  counterparts  of  the  marginal  crevasses 
are  formed  in  them  and  trend  down  stream,  and  are  practically  continuous 
with  the  breaks  in  the  margin  of  the  glacier  itself.  The  marginal 
crevasses  in  the  glacier  and  the  similar  breaks  in  the  adjacent  bank, 


INTUODUCTION. 


11 


rms  in  the 

Y  that  the 

)hitheatre8 

relief  of 

ancf  fail  in 
fragments 
and  the  ice 
completely 
all  degrees 
8  of  steep 
f  the  snow 

of  feet  in 
3r  architec- 
of  glacier- 
Alaska,  the 
forms  par- 
he  ruins  of 
ice  is  more 
escents  are 
lid  angular 

are  much 
ar  descents 
ixperienced 

bed,  it  is 
widest  just 
ring  stream 
■  a  glacier. 
I  bi-ckward 
ighborhood 
ies  of  well- 
more  rapid 
it  angles  of 
janks  of  an 
,1  crevasses 
continuous 
e  marginal 
,cent  bank. 


however,  are  separated  by  a  band  of  shattered  snow  sometimes  several 
rods  b'-oad,  which  sharply  defines  the  margin  «>f  the  current.  These 
crevassed  banks  of  snow  and  ice  are  common  in  the  St.  IClias  region,  and 
have  been  d'scrilxjd  by  tlie  writer.* 

In  the  ciise  of  glaciers  that  expand  on  leaving  narrow  volleys,  stresses 
are  produced  in  other  directions  than  in  the  cases  cited  above,  and  longi- 
tudinal or  more  or  less  regularly  radiating  breaks  are  produced.  A  well- 
known  instance  of  this  nature  is  furnished  by  Rhone  glacier. 

It  may  be  judged  from  this  brief  sketch  that  the  conditions  leading  to 
the  fracture  of  moving  ice  masses  uro  exceedingly  varied  an«l  pro(hice 
diveree  results.  The  series  of  more  regularly  arranged  fractures,  to  which 
special  attention  has  l)een  directed,  are  united  by  other  and  less  easily 
explained  breaks,  so  that  the  detail  of  the  surface  of  an  ice  stream,  espe- 
cially when  modified  by  melting,  becomes  at  times  wondeifuUy  complex. 
It  is  only  by  selecting  isolated  and  well-defined  instances  for  study  that 
the  laws  governing  the  behavior  of  ice  under  the  varied  stresses  produced 
in  flowing  through  irregular  valleys  and  over  rough  surfaces  can  be  at  all 
understood. 

The  ice  of  glaciers  is  also  broken  along  planes  more  or  less  inclined  to 
their  surfaces.  Movement  takes  place  along  these  breaks,  and  produces 
thrusts,  analogous  to  the  over-thrusts,  or  under-thrusts,  sometimes  seen 
in  rocks  that  have  been  folded  and  broken.  In  fact,  the  counterpart  of 
many  of  the  structural  features  observed  in  rocks,  such  as  faults,  folds, 
joints,  contortions,  etc.,  may  be  observed  in  the  ice  of  glaciers. 

Surface  Features.  —  Owing  to  the  presence  of  crevasses  and  to  unequal 
melting,  the  surfaces  of  glaciei-s  are  frequently  exceedingly  rough  and 
irregular.  Foreign  matter  resting  on  the  ice,  when  sufficiently  thick  not 
to  be  warmed  through  by  the  sun's  lieat  in  a  single  day,  protects  the  ice 
beneath,  while  adjacent  surfaces  not  so  protected  are  lowered  by  melting. 
Blocks  of  stone  thus  shelter  the  ice  beneath  and  remain  on  i)illars  or  ped- 
estals as  the  surrounding  surface  is  lowered.  A  group  of  such  "  glacier 
tables,"  as  they  are  called,  is  shown  on  page  44.  Tliese  were  observed 
by  the  writer  on  a  small  glacier  on  the  High  Sierra  of  California,  and 
present  a  fair  idea  of  the  character  of  the  mushroom-shaped  prominences 
common  on  many  glaciere.  Glacier  tables  frequently  incline  southward 
in  north  temperate  latitudes,  owing  to  the  greater  melting  of  their  sup- 

1  "An  Expedition  to  Mount  St.  Ellas,  Alaska,"  National  Geographic  Magazine 
(Washington,  D.  C),  vol.  3,  pp.  127,  128. 


13 


GLACIERS   OF   NOKTU   AMERICA. 


poitinp  columns  on  tho  Houth  side.  Eventually,  the  uprawed  block  slips 
off  its  pedestal  in  a  southerly  direction,  leaving  a  stunij)  of  ice  to  mark 
its  site.  When  this  happens,  the  process  is  renewed  and  the  hlock  aj^ain 
left  in  relief  by  the  meltinpf  of  the  surrounding  surface.  'J'lie  boulders 
and  stones  carried  on  the  surface  of  glaciei-s  thus  receive  many  falls, 
and  Inicome  broken  and  more  or  less  comminuted.  This  illustrates  the 
fact  that  not  all  of  the  crushing  and  commingling  of  rocks  performed  by 
a  ghuuer  takes  place  deep  within  or  beneath  its  mass. 

Moraines  on  the  surfaces  of  glaciiei-s  are  composed  in  a  great  measure 
of  blocks  of  stone,  whic^h  protect  the  ice  beneath,  as  stated  above,  and 
produce  still  more  marked  ine<iualities  of  the  surface.  What  appear  to 
be  massive  embankments  of  ."tones  and  dirt  are  many  times  ridges  of  ice 
covered  witli  a  veneer  of  debris  only  a  foot  or  two  thick.  The  slow  melt- 
ing of  the  ice  beneath  superficial  moraines  causes  the  larger  and  less 
angular  stones  to  slide  and  roll  down  the  sides  of  the  ridges,  thus  lead- 
ing to  a  rude  assortment  of  the  material,  with  reference  to  size  and 
sliJipe.  Sudi  an  assorting  may  l)e  seen  in  the  side  view  of  a  medial 
moraine  shown  in  Figure  H.  Tiie  friction  and  impact  of  the  frequently 
disturbed  roctks  cause  breakage  and  the  formation  of  angular  gravel,  and 
even  clay.  Disintegration  and  weathering  are  thus  j)romoted,  and  the 
surface  material  becomes  divided  into  smaller  and  smaller  masses  the  far- 
ther it  is  carried  or  the  longer  it  remains  on  the  ice. 

When  there  are  several  i)arallel  moraines  on  a  glacier  the  surface 
becomes  exceedingly  rugged ;  and  when,  in  addition,  creviisses  cross 
such  a  region,  it  is  frequently  rendered  entirely  impassable.  I  well 
remember  a  long,  weary  march  across  the  Malaspina  glacier,  when  our 
route  lay  at  right  angles  to  fully  a  score  of  huge  moraines,  each  one 
forming  a  ridge  from  50  to  200  feet  broad  at  the  top,  and  rising  100  or 
150  feet  above  the  adjacent  troughs.  These  ridges  were  completely 
sheathed  with  stones  held  in  sockets  of  ice,  which  would  frequently  slip 
from  beneath  our  feet  and  roll  to  the  bottom  of  the  escarpment.  The 
sides  of  these  ridges  were  so  steep  that  we  could  ascend  them  only  by 
choosing  zigzag  courses.  Many  were  the  slips  and  tumbles  experienced 
during  the  day.  Between  the  ridges  that  caused  so  much  delay  and 
fatigue,  there  were  lanes  from  a  hundred  to  several  hundred  yards  broad, 
floored  with  comparatively  smooth  ice,  which, had  been  deepened  by  the 
melting  of  the  glacier,  where  unprotected.  When  standing  on  the  crests 
of  the  dark,  stone-covered  ridges  one  could  trace  their  courses  for  miles 
on  either  har  d,  until  a  change  in  the  slope  of  the  glacier  carried  them 


INTKODICTION. 


18 


the  surface 


out  of  view.  At  rij?ht  angles  to  tiieir  tren<l  there  was  nothing  in 
Hi^ht  except  the  (llHtaiit  niountaiiiH  und  the  Heeniingly  eiullesa  expunse 
of  hiirrtiii  and  exceedingly  desolate  dehris. 

MaHses  of  sand  and  gravel  renting  on  ice  behave  in  nnu-h  the  same 
manner  as  <lo  rock  masses  and  moraines,  except  that  wln^re  they  are  left 
upraised  alK)ve  the  wasting  surface  the  grains  and  pebhles  roll  ami  slide 
downward,  and  the  pedestal  is  transformed  into  a  cone  of  ice  sheathed 
with  a  thin  covering  of  loose  njaterial.  At  times,  many  acres  far  out 
on  a  glacier,  are  studded  with  groups  of  these  peculiarly  regular  cones 
or  pyramids,  from  a  few  inches  to  ten  or  twelve  feet  in  height.  Not 
infrecpiently  tluy  lH»ar  a  striking  resemblance  to  Indian  tei)ees  ;  in  fact, 
one  might  easily  mistake  a  group  of  these  structures  for  an  Indian  en- 
campment. 

Still  greater  inecpialities  occur  when  moraines  rest  on  stagnant  ice  and 
basins  holding  lakelets  are  formed.  The  sides  of  these  depressions  melt, 
and  the  stones  and  dirt  previously  spread  out  as  a  general  morainal  cov- 
ering over  the  surface  fall  into  them.  The  surface  material  thus  l)ecome8 
locally  concentrated.  As  melting  progresses,  the  lakes  are  drained. 
These  thick  accumulations  of  debris  protect  the  ice  beneath  and  become 
elevated  in  the  same  manner  as  the  sand  cones  descriljed  above;  but  the 
mass  of  the  material  being  greater,  and  frequently  containing  large  boul- 
ders, the  cones  fc»rmed  are  of  large  size,  and  in  many  instances  have  an 
elevation  of  i)0  to  150  feet.  Although  looking  like  pyramids  of  rudely 
piled  bouldei-s,  one  finds  on  climbing  their  sides  that  they  are  really 
pyramids  of  ice  with  a  comparatively  thin  sheathing  of  stones  and  dirt. 
Large  bouldei-s,  i)erched  on  the  summits  of  these  rugged  ]>yramids, 
become  detached  from  time  to  time,  and  descend  in  small  avalanches  to 
the  depressions  below,  illustrating,  again,  the  process  of  breaking  and 
disintegration  which  takes  pLice  in  the  debris  covering  the  surfaces  of 
glaciera. 

While  large  rocks  or  thick  masses  of  dirt  and  stones  resting  on  ice  pro- 
tect it  from  melting,  the  reverse  is  the  case  Avith  pebbles  and  other  small 
objects,  particularly  those  of  a  dark  color,  which  become  Avarmed  through 
by  the  sun's  heat  during  a  single  day,  and  lead  to  the  melting  of  the  ice 
beneath.  Such  bodies  sink  into  the  ice  and  are  commonly  found  at  the 
bottoms  of  little  water-filled  wells  five  or  six  inches  deep.  On  glaciers, 
where  there  is  a  scanty  covering  of  pebbles,  each  individual  stone  will 
be  found  at  the  bottom  of  a  water-filled  depression.  Sometimes  the 
holes  are  so  abundant  that  in  walking  over  the  surface  one  really  treads 


14 


GLACIERS   OF  NORTH   AMERICA. 


on  the  summits  of  thickly  set  columns  of  ice,  separating  the  depressions. 
Leaves  are  frequently  blown  far  out  on  glaciers,  and  becoming  warmed 
by  the  sun  sink  into  the  ice  in  the  same  manner  as  the  pebbles  already 
refeiTcd  to,  and  even  insects,  especially  butterflies,  are  conspicuous  in 
such  localities.  Op  one  occasion,  when  traversing  an  ice  stream  tribu- 
tary to  Malaspina  glacier,  I  found  a  fish,  about  four  inches  long,  at  the 
bottom  of  one  of  these  holes.  The  nearest  water  in  which  it  could  have 
lived  was  at  least  twenty  miles  away.  The  most  probable  supposition  is 
that  it  had  been  carried  to  the  place  where  found  by  a  bird. 


iijli 
ill 


Meltin§r  and  Drainage.  —  The  silence  on  broad  glaciers  when  the  winds 
are  still  and  the  temperature  below  freezing  is  frequently  oppressive. 
This  is  especially  noticeable  on  summer  nights,  for  after  sunset  even  in 
summer  the  teiaperature  falls  below  freezing  on  the  surfaces  of  large 
glaciers  ;  but  when  the  morning  sun  warms  the  air,  rills  and  ri  v^ulets  are 
formed,  a'.id  the  murmuring  of  running  water  is  heard  on  every  hand. 
By  midday,  brooks  and  creeks,  too  deep  and  rapid  to  wade  and  too  broad 
to  vault  over,  are  coui'sing  along  In  channels  of  ice.  But  their  exist- 
ence is  brief.  Soon  a  crevasse  is  reached,  and  their  floods  pour  down 
into  the  depths  of  the  glacier  with  a  deep  roar,  telling  of  caverns  far 
below  the  surface.  The  crevasses  into  which  surface  streams  find  their 
way  are  frequently  enlarged,  and  become  well-like  openings,  or  moulina, 
as  they  are  termed,  which  are  sometimes  several  yards  in  diameter,  and 
of  great  depth.  In  many  instances,  these  openings  must  penetrate  to 
the  very  bottom  of  a  glacier.  When  this  happens,  the  bould'^"3  and 
stones  that  find  their  w.  into  them  are  washed  about,  and  are  given 
a  rotary  motion  by  the  descending  waters,  so  as  to  act  as  veritable  mill- 
stones, and  grind  the  rocks  beneath.  The  result  of  this  action  is  the 
formation  of  pits  and  holes  in  the  rocks,  resembling  kettles,  and  termed 
pot  holes,  in  which  the  stones  that  made  them  may  frequently  be  found. 
These  peculiar  excavations  are  Avell  known  in  regions  of  former  glaci- 
ation.  Typical  examples  in  the  Glacier  garden,  near  Lucerne,  Swit- 
zerland, are  familiar  to  many. 

The  surface  melting  of  glaciers  leads  to  the  formation  of  broad,  shal- 
low lakes.  These  appear  especially  on  the  neves,  and  by  the  intensity 
of  their  deep  blue  color  impart  an  additional  charm  to  the  wintry  scenes 
reflected  from  their  surfaces.  The  chores  of  such  lakos  afford  favorable 
camping  places  for  glacier  explorei-s,  since  water,  the  only  necessity  of 
camp  life  to  be  found  in  such  regions,  can  there  be  had  without  the 


UNTKODUCTION. 


15 


expense  of  time  and  fuel  necessary  to  procure  it  by  melting  snow. 
Many  times  during  two  expeditions  conducted  by  the  writer  on  the 
broad  n6\e  fields  of  southern  Alaska,  we  had  occasion  to  pitch  our 
tent  by  the  shores  of  these  snow-bound  Lakes,  and  fully  appreciated  the 
advantages  they  afforded.  In  other  instances,  when  necessity  required 
us  to  camp  on  greatly  crevassed  snow,  our  water  supply  was  bometimes 
obtained  from  the  crevasses  by  means  of  a  bucket  attached  co  a  line. 

tf  he  water  formed  on  the  surfaceii  of  glaciei-s,  and  draining  from  the 
land  surrounded  by  them,  or  lying  in  front  and  sloping  to^^  irds  them, 
finds  its  way  into  the  ice  and  escapes  by  tunnels  situated  either  at  the 
bottom  of  the  glacier  or  in  the  ice  itself.  At  the  ends  of  alpine  glaciers, 
and  about  the  margins  of  both  piedmort  »rd  continental  ice  sheets,  there 
are  ice  caverns  from  which  flow  turbid  streams  of  ice-cold  water.  (Fig.  B, 
Plate  17.)  The  archways  are  the  mouths  of  tu.^ne^"  into  which  one 
can  sometimes  penetrate  for  a  long  distance.  The  sti:.ams  issuing  from 
such  openings  are  supplied  by  both  surface  and  basal  melting,  and  pos- 
sibly also  by  subglacial  springs.  These  tunnels  appear  in  all  stages  of 
glacier  growth,  and  are  kept  open  even  when  ice  sheets  reach  great  dimen- 
sions. On  Malaspina  glaciers,  the  course  of  such  tunnels  csin  in  some 
instances  be  followed  for  miles,  by  listening  to  the  muflBed  roar  of  the 
rivers  rushing  along  through  »oe  caverns  far  below  the  surface.  Some  of 
the  tunnels,  through  which  the  waters  formed  by  the  melting  of  glaciars 
escape,  are  known  to  be  situated  on  the  underlying  rock,  but  in  other 
instances  the  openings  traverse  the  ice  itself,  perhaps  several  hundred  feet 
above  its  bottom.  The  tunnels  through  the  body  of  the  ice  are  thought 
to  have  originated  from  crevo,sses  which  allowed  the  surface  water  to 
escape  from  one  break  to  another,  and  maintain  a  continuous  passage-way. 
But  observations  proving  this  to  be  the  true  explanation  are  wanting. 
In  the  sides  cf  deep  crevasses  in  the  Malaspina  glacier  one  some- 
times discover  a  circular  openiug  several  feet  in  diameter,  which  reveals 
the  position  of  an  abandoned  tunnel.  In  traversing  the  extremely  rough 
outer  margin  of  the  glacier  leferred  to,  these  openings  were  at  times 
of  great  assistance,  as  they  allow  an  explorer  to  pass  from  one  deep 
valley  in  the  ice  to  another,  and  thus  avoid  a  steep  climb  over  moraine- 
covered  ice. 

The  drainage  of  glaciers,  particularly  those  of  the  piedmont  and  conti- 
nental types,  is  of  special  geological  interest,  for  the  reason  that  vast 
quantities  of  mud,  sand,  gravel,  etc.,  are  carried  into  the  tunnels  through 
which  the  sub-  and  engJacial  streams  flow,  and  either  left  on  the  bottoms  of 


^^ 


16 


GLACIERS    OP    NORTH    AMERICA.. 


i     ;i 


the  channels,  or  swept  out  at  the  margins  of  the  ice  and  deposited  in  part 
over  the  adjacent  land.  The  sediments  now  forming  about  the  border  of 
Malaspina  glacier  are  of  great  volume,  and  of  more  geological  interest 
than  even  the  abandoned  moraines  left  by  the  slowly  retreating  ice  mass. 
As  will  be  described,  thousands  of  acres  of  dense  forest  are  there  being 
overwhelmed  and  buiied  by  the  deposits  of  streams,  that  pour  out  from 
tlie  ice,  heavily  freighted  with  sediment  and  even  sweeping  along  large 
bouldei-s.  * 

The  chief  characteristic  of  the  streams  that  emerge  from  beneath 
glaciers  is  their  peculiar  turbidity  or  milkiness.  In  exploring  regions 
where  the  glaciers  are  small  and  hidden  in  sheltered  recesses  about  high 
peaks,  one  is  frequently  enabled  to  discover  them  by  noting  the  character 
of  the  waters  flowing  from  the  mountains.  Upland  streams  not  fed  by 
melting  glaciers  are  usually  clear  and  sparkling,  except  during  stoiTis, 
while  those  born  in  ice  caverns  are  rendered  opalescent,  and  have  a  pecu- 
liar greenish-yellow  tint,  on  account  of  the  extremely  fine  material  sus- 
pended in  them.  This  fine  rock  flour,  as  it  is  termed,  is  retcined  in  sus- 
pension even  after  the  streams  emerge  from  the  highlands  and  flow  through 
adjacent  plains.  Deposits  of  fine  sediment  of  peculiar  geological  interest 
are  formed  by  such  streams,  and  enable  one  to  interpret  similar  accumula- 
tions termed  loess,  left  about  the  margins  of  ice  sheets  that  have  now  passed 
away,  and  along  the  stream  channels  leading  ^'-om  them.  The  bluffs  of  fine, 
yellowish,  clay-like  material  along  the  Mississippi  and  Missouri  are  of  this 
character.  '      , 

What  is  a  Glacier? 

The  preceding  paragraphs  contain,  I  believe,  an  enumeration  of  the 
principal  characteristics  of  glaciers.  Although  it  is  diflicult,  and  perhaps 
impossible,  to  frame  a  concise  definition  of  a  glacier  which  will  embrace 
all  ice  bodies  that  should  be  properly  included,  and  exclude  other  accumu- 
lations of  snow  and  ice  to  which  the  name  should  not  be  applied,  5^et  it 
seems  safe  to  assert  that  any  considerable  mass  of  snow  and  ice  which 
presents  a  number  of  the  characteristics  referred  to  above  may  with 
propriety  be  included  in  the  term. 

As  a  provisional  definition,  it  may  be  said  that  a  glacier  is  an  ice  body 
originating  from  the  consolidation  of  snow  in  regions  where  secular  accu- 
mulation exceeds  melting  and  evaporation,  i.e.  above  the  snow  line,  and 
flowing  to  regions  where  waste  exceeds  supply,  i.e.  below  the  snow  line. 
Accompanying  these  primary  conditions  are  many  secondary  phenomena 


INTRODUCTION. 


17 


dependent  upon  environment,  such  as  the  grain  of  the  ice,  crevasses,  melt- 
ing, laminations,  dirt  bands,  moraines,  glacier  tables,  ice  pyramids,  sand 
cones,  et(f.,  which  may  or  may  not  be  present.  Glaciers,  even  of  large 
size,  may  exist  in  which  few  and  perhaps  none  of  these  details  can  be  dis- 
covered. We  may  conceive  of  a  glacier  as  flowing  through  a  channel  so 
even  and  so  well  adjusted  to  its  progress  that  no  crevasses  will  be  formed. 
So  little  debris  may  reach  its  surface  that  moraines  and  all  accompanying 
details  will  be  absent.  The  most  persistent  features  of  an  ice  stream 
are,  perhaps,  the  slow  movement  or  downward  flow  in  both  the  neve  and 
ice  regions,  the  stratification  of  the  neve,  and  the  laminated  structure 
and  grain  of  the  glacier  proper.  Yet  even  these  important  characteristics 
may  not  be  readily  discernible,  even  in  ice  sheets  that  are  unques- 
tionably true  glaciers.  Although  the  brief  definition  given  above  may 
assist  one  in  obtaining  an  idea  of  what  constitutes  a  glacier,  it  is  mani- 
festly open  to  qualifications  and  exceptions.  If  we  consider  the  snow  line 
as  defining  the  boundary  between  the  neve  and  the  glacier  projjcr,  it  is 
evident  that  there  must  be  numerous  exceptions  to  the  rule.  As  before 
remarked,  during  certain  yeai"s,  and  at  times  for  many  years  in  succession, 
the  snow  line  is  much  lower  than  at  other  times,  and  may  even  completely 
conceal  the  hard  ice  which  usually  protrudes  below  the  neve.  Again,  an 
ice  stream  may  end  in  the  sea,  and  be  broken  off  and  float  away  as  bergs, 
before  the  division  into  neve  and  glacier  proper  is  distinguishable  on  the 
surface.  One  of  the  most  characteristic  features  of  glaciers  is  their  slow 
flowing  motion,  yet  in  their  old  age  this  may  cease,  so  that  the  limits 
between  a  true  ice  stream  and  an  inert  ice  mass  may  be  indefinite,  and 
perhaps  impossible  to  define. 

From  what  has  been  learned  concerning  glaciers  it  is  evident  that  they 
form  »ne  of  the  transition  phases  in  the  history  of  drainage  in  many 
regions,  and  that  the  variations  they  present,  like  genera  and  species  in 
the  organic  kingdom,  cannot  be  limited  by  hard  and  fast  lines,  but  should 
be  classified  by  means  of  comparisons  with  typical  examples.  From  snow, 
hail,  and  frozen  mists,  usually  on  elevated  regions,  the  granular  ice-snow 
of  a  neve  is  formed.  By  pressure  and  alternate  softening  and  re  freezing 
the  n^ve  is  changed  into  compact  glacial  ice,  but  the  plane  of  separa- 
tion is  indefinite,  and  no  one  can  say  where  in  a  vertical  section,  the  nev6 
ends  and  the  true  glacial  ice  begins.  Both  the  neve  and  the  glacier 
proper  are  wasted  hy  melting  when  ihe  temperature  is  above  32°  of 
the  Fahrenheit  scale,  and  the  solid  drainage  is  transformed  to  a  liquid 
co'^dition. 


I 


18 


GLACIERS    OF   NOUTH   AMERICA. 


'!  Ill 


;'# 


Glacial  Abrasion. 

■Worn  and  Striated  Kock  Surfaces.  —  The  movement  of  glacial  ice 
causes  friction  and  leads  to  the  grinding,  smoothing,  and  scratching  of 
the  rocks  over  which  it  passes.  The  intensity  of  this  grinding  can  be 
appreciated  to  some  extent  by  considering  the  force  with  which  a  thick 
ice  mass  presses  on  the  rocks  beneath.  The  weight  of  a  cubic  foot  of  ice 
is  about  fifty-seven  pounds;  hence  a  glacier  1000  feet  thick,  which  is  by 
no  means  the  maximum,  would  exert  a  pressure  on  its  bed  of  twenty-eight 
tons  to  the  square  foot.  A  movement  of  ice  charged  with  sand  and 
stones  under  such  a  pressure  cannot  fail  to  produce  abrasion  of  the 
rocks  beneath. 

As  will  be  shown  in  a  future  chapter  devoted  to  theories  of  glacial 
motion,  the  precise  mechanics  of  glacial  flow  is  not  clearly  understood. 
It  is  well  known,  however,  that  the  ice  is  not  forced  along  as  a  rigid  body. 
If  such  were  the  case,  the  grinding  would  be  far  more  intense  than  is  now 
believed  to  occur.  It  is,  also,  known  that  the  flow  of  glacial  ice  is  at  least 
analogous  to  the  flow  of  what  are  commonly  considered  plastic  solids,  as 
pitch,  for  example.  In  an  ice  stream  the  movement  is  most  rapid  at  the 
surface  at  a  distance  from  its  borders,  and  decreases  toward  the  bottom 
and  sides,  where  the  friction  is  greatest.  Under  similar  conditions  the 
movement  of  clear  ice  is  greater  than  when  it  is  charged  with  ddbris. 
The  study  of  glaciers  has  shown,  also,  that  sometimes  the  ice  is  sheared, 
and  a  forward  movement  is  accomplished  by  a  thrust  of  the  upper  portion 
of  the  mass  over  the  lower  portion.  However  accomplished,  the  fact 
remains  that  there  is  frequently  a  movement  of  even  the  saud-charged 
layers  at  the  bottom,  and  that  friction  does  occur  between  the  ice  and  the 
underlying  rock. 

The  conditions  governing  the  flow  of  glaciers  are  so  complicated  that 
varying  results  are  to  be  expected.  When  the  bottom  layer  is  heavily 
charged  with  debris,  and,  especially  when  containing  a  large  proportion 
of  gravel  and  stones,  the  friction  is  increased,  and  may  possibly  become 
so  great  that  the  bottom  layer  will  be  practically  stagnant  and  allow 
the  clearer  ice  above  to  flow  over  it ;  or  a  shearing  of  the  mass  may 
result,  and  the  lower  portion  remain  stationary  for  a  time,  while  the 
upper  portion  moves  on.  Probably  the  mo&t  favorable  conditions  for 
rock  abrasion  are  when  the  bottom  of  a  glacier  is  lightly  charged  with 
sand,  and  the  surface  of  contact  with  the  rocks  beneath  is  lubricated  with 
water.     That  glaciers  abrade  the  rocks  over  which  they  pass,  as  already 


til 


INTRODUCTION. 


19 


stated,  there  is  abundant  evidence.  At  the  lower  end,  and  along  the 
[sides  of  many  alpine  glaciers,  the  ice  charged  with  sand  and  stones  may 
be  seen  in  direct  contact  with  the  smooth,  polished,  and  striated  rock 
surfaces.  Below  glaciers  that  have  recently  retreated,  and  where  the 
surface  is  still  bare  of  vegetation,  records  similar  to  those  jubt  mentioned 
may  be  observed  in  thousands  of  localities.  The  same  is  true,  also,  over 
vast  regions  that  are  known  to  have  been  formerly  glaciated  ;  \*hile  on 
adjacent  areas,  where  the  c  nditions  are  similar,  excepting  that  they  were 
not  occupied  by  ice,  the  peculiar  and  not  easily  mistaken  evidences  of  ice 
abrasion  are  lacking.  vVe  have,  therefore,  both  positive  and  negative 
evidence  pointing  to  the  conclusion  that  glaciers  abrade  the  rocks  over 
which  they  flow. 


Smoothed  and  Stria teu         k  Surfaces  not  Produced  by  Glaciers.  — 

There  are  markings  that  simulate  glacial  polishing  and  striation,  an '. 
might  be  mistaken  for  them,  but  are  produced  by  other  agencies.  River 
ice,  especially  when  swept  along  by  freshets,  sometimes  scratches  and 
striates  the  rocky  ledges  with  which  it  comes  in  contact,  but  this  action  is 
confined  within  narrow  vertical  limits,  and  the  marks  produced  are  by  no 
means  so  regular,  or  so  deeply  engraved,  as  those  frequently  made  by 
glaciers.  The  abrasion  of  river  ice  was  observed  by  the  writer  under 
favorable  conditions  along  the  Yukon  river,  but  it  did  not  appear  as  if  the 
smoothing  and  striation  produced  in  that  way,  except,  perhaps,  when  only 
limited  exposures  were  observable,  could  be  easily  mistaken  for  the  work 
of  glaciers. 

The  action  of  floe  ice  on  the  shores  of  lakes  and  northern  oceans,  when 
driven  landward  by  wind  pressure,  on  shelving  beaches,  makes  the  nearest 
approach  to  glacial  abrasion  and  striation  that  is  known.  Except  that  the 
action  of  floe  ice  is  confined  to  narrow  vertical  limits,  it  is  difficult  to 
understand  how  the  planing  and  striation  it  produces  on  the  rocks  bene  ith 
could,  in  the  absence  of  other  data,  be  distinguished  from  the  work  of 
glaciers.  Glaciers  smooth  and  striate  vertical  walls,  Jis  well  as  flat  sur- 
faces, however,  and  make  these  and  other  records  at  all  elevations  from 
the  surface  of  the  sea  —  and  to  a  limited  extent  even  below  sea  level  — 
up  to  the  summits  of  lofty  mountains.  It  is  to  be  expected,  also,  that 
the  records  of  floe  ice  would  be  accompanied  by  other  evidence,  such  as 
deposits  of  clay  and  sand  containing  marine  or  lacustral  shells,  and  topo- 
graphic features  due  to  the  abrasion  and  deposition  produced  by  waves 
and  currents.    When  a  considerable  body  of  evidenca  is  in  hand  in  connec- 


20 


GLACIERS    OF    NORTH    AMERICA. 


m ' 


tion  with  the  abrasion  of  ro(  k  surfaces  in  a  given  locality,  there  usually 
remains  no  room  for  doubting  in  what  way  tlie  planing  and  striation  were 
produced. 

Special  Features  of  Glaciated  Surfaces.  —  The  minor  changes 
produced  on  rock  surfaces  by  the  movement  of  ice  over  th^m  are 
so  numerous  that  attention  can  only  Ix-  directed  at  this  time  to  those 
that  are  most  common  and  most  characteristic.  The  details  of 
these  wonderful  inscriptions  can  only  be  appreciated  by  studying  the 
originals. 

Rock  si;rfaces  that  have  been  subjected  to  the  grinding  of  an  ice  sheet, 
or  crossed  by  even  a  small  alpine  glacier,  are  frequently  found  to  be 
worn  and  the  angles  and  prominences  rounded  and  planed  away.  All 
weathered  and  oxidized  portions  of  the  preglacial  surface  are  removed, 
and  the  fresh  hard  ro  k  exhibits  a  polish  approaching  that  given  by 
marble-workers  to  finished  monuments.  The  hardest  and  finest-grained 
rocks  receive  the  most  brilliant  polish.  Limestone,  granite,  and  quartzite, 
especially,  are  frequently  so  highly  burnis)ied  that  they  glitter  in  the 
sunlight  with  dazzling  brilliancy.  On  such  surfaces  there  are  usually 
scratches  and  grooves,  frequently  in  long,  parallel  lines,  which  show  the 
direction  in  which  the  ice  moved  over  them.  These  markings  vary  in 
size  from  delicate,  hair-like  lines,  such  as  might  be  made  by  a  crystal 
point,  to  heavy  grooves  and  gouges,  a  foot  and  sometimes  several  feet 
deep,  which  frequently  run  in  one  general  direction  for  many  yards 
and  even  several  rods,  and  indicate  by  their  straightness  and  evenness 
that  the  engine  which  made  them  was  one  of  great  power  and  m-^ved 
steadily  in  a  continuous  direction.  In  regions  formerly  occupied  by 
continental  glaciers,  particularly,  two,  and  possibly  three,  well-defined 
series  of  parallel  striations  are  sometimes  observable  on  the  same  sur- 
face, crossing  each  other  at  varying  angles.  The  most  probable  explana- 
tion of  these  double  or  triple  inscriptions  is  that  the  direction  of  the 
ice  current  varied  with  the  growth  and  decline  of  the  glacier  which 
made  them,  or  that  the  ice  flowed  in  great  swirls  or  eddies,  as  in  the 
case  of  the  Malaspina  glacier,  and  that  the  direction  of  these  currents 
changed  with  variations  in  the  volume  of  the  glacier,  or  perhaps  with 
variations  in  the  amount  of  ddbris  in  the  ice.  On  small  areas  the 
parallel  striations  appear  straight,  but  if  one  could  examine  square  miles 
of  surface  it  would  probably  be  found  that  the  lines  are  frequently 
portions  of  broad  curves. 


INTRODUCTION. 


21 


3re  usually 
iation  were 


)!•  changes 
thbin   are 

le  to  those 
details    of 

iclying  the 

n  ice  sheet, 
iind  to   be 
away.     All 
e  removed, 
it  given  by 
lest-grained 
d  quartzite, 
tter  in  the 
are    usually 
!h  show  the 
ngs  vary  in 
y  a   crystal 
several  feet 
many  yards 
id  evenness 
and  m^ved 
ccupied   by 
well-defined 
3  same  sur- 
)le  explana- 
ion  of   the 
acier  which 
s,  as  in  the 
se  currents 
irhaps  with 
areas    thr 
quare  miles 
frequently 


Occasionally  the  more  strongly  marked  glacial  grooves  in  resistant 

i  rocks,  like  hard    limestone  and  quartzite,  exhibit   curved  or  semilunar 

cracks,  which   cross   the    furrows    from    side    to  side  at  quite  uniform 

j  intervals  of  a  fraction  of  an  inch  up  to  au  inch  or  more,  and  are  con- 

jvex    in    the    direction    of   the    former   ice  movement.     These  "chatter 

marks"  are  thought  to  have  been  formed  by  pebbles  that  were  checked 

in  their  movement  by  friction,  and  when  the  force  became  sufficient  to 

carry  them  onward,  were  forced  forward  suddenly,  perhaps  turning  over, 

land  struck  the  rock  with  such  force  as  to  produce    cmcks.     A  similar 

[action  may  be  observed  in  sliding  bodies,  as  wlien  the  wheels  of  a  car 

[slide  on  the  track  and  a  jar  is  felt  when  they  slip   and   are    arrested. 

[These  peculiar  semilunar  cracks  are  not  confined  to  bottoms  of  grooves, 

however,  but  appear  on  flat  surfaces,  where  they  are  sometimes  two  or 

three  inches  or  more  in  length,  and  are  separated  by  intervals  fully  as 

great.     These  larger  cracks,  or  "  disrupted  gouges,"  as  Chamberlin  has 

called  them,  are  concave  toward  the  point  of   the  compass  from  whicu 

[the  ice  came. 

Another  characteristic  feature  of  glaciated  surfaces  is  observed  when 
[hard  knobs  occur  in  rock,  as,  for  example,  when  limestone  is  charged 
with  small  masses  of  chert,  or  with  silicified  shells  and  corals.  In 
[such  instances  the  hard  portions  are  left  in  relief  by  the  abrasion  of 
the  softer  matrix.  Starting  from  each  elevation  there  are  frequently 
[raised  ridges,  tapering  to  a  point  in  the  direction  of  the  ice  movement, 
land  showing  the  manner  in  which  the  soft  rock  in  the  lee  of  the  prom- 
linences  was  protected.  On  the  opposite  side  of  such  knobs,  i.e.  on 
[the  side  from  which  the  ice  came,  the  rock  is  sometimes  worn  into  a 
[furrow,  which  bends  around  the  obstruction,  and  from  its  form  indi- 
[cates  that  the  ice  behaved  as  a  plastic  body  and  moulded  itself  to  the 
Isurface  over  which  it  flowed. 

Many   other   features    of   ice-worn    surfaces    might   be  enumerated, 
nit    in    an   elementary  introduction  it  is  perhaps  better  not  to  burden 
Jthe  reader  with  details.^ 

1  In  the  report  on  "The  Rock  Scorings  of  the  Great  Ice  Invasion,"  byT.  C.  Chamber- 
in,  in  the  7th  Annual  Report,  U.S.  Geological  Survey,  the  reader  will  find  many  illustra- 
lions  of  ice  abrasion,  accompanied  by  clear  and  concise  explanations  of  the  manner  of 
their  formation,  which  will  enable  him  to  interpret  such  inscriptions  for  himself  wherever 
ifound. 


22 


GLACIERS    OF   NORTH    AMERICA. 


'Ill  fi 


Glacial  Deposits. 

The  morainnl  material  carried  by  glaciers  either  on  their  surfaces 
or  within  their  mass,  is  left  when  they  melt,  and  forms  accumulations 
to  which,  in  part,  the  term  moraine  is  still  applied.  The  characteristics 
of  such  abandoned  moraines  are  frequently  well  exhibited  in  mountain 
valleys  from  which  glaciers  have  recently  retreated.  The  most  common 
of  these  deposits  are  briefly  described  below. 

Lateral  Moraines.  —  The  debris  accumulated  on  the  borders  of  an 
ice  stream,  and  constituting  the  lateral  moraines  of  a  living  glacier,  is 
left  when  the  ice  melts  and  appears  as  a  ridge  or  terrace  at  varying  I 
elevations.  Steep-sided  mountain  valleys  are  frequently  bordered  on 
either  side  by  ridges  of  this  character,  which  may  be  situated  1000  feet 
or  more  above  the  bottom  of  the  trough  and  clearly  traceable  for  miles. 
On  the  precipitous  sides  of  such  valleys,  above  the  highest  of  the 
abandoned  moraines,  the  slopes  are  usually  rough  and  irregular,  and 
bear  evidence  of  the  work  of  streams  and  rills  descending  from  higher 
elevations,  as  well  as  other  results  of  atmospheric  waste  ;  while  below 
the  horizon  referred  to  the  relief  is  subdued,  and  the  valley  has  the 
smooth  and  flowing  contours  characteristic  of  ice  work.  Moraines  of 
this  character  are  frequently  similar  to  stream  terraces,  but  usually  | 
have  a  raised  outer  margin,  and  besides  are  composed  of  angular  and 
unassorted  material. 

Terminal  Moraines.  —  At  various  stages  in  the  retreat   of   an    ice 
stream,  the    lateral    moraines    on    its   sides    are   united   by  a  terminal 
moraine,  which  crosses  the  abandoned  bed  of   the  glacier  and  forms  a  | 
somewhat  regular  and  usually  crescent-shaped  pile  of  stones,  gravel,  and  | 
sand,  which  is  convex  down  stream  and  in  many  instances  100  feet  or  more 
in  thickness.     Between  successive  terminal  moraines  the  bottom  of  the 
trough  may  be  deeply  filled  with  morainal  material,  deposited  without 
special    arrangement,    and    in    many   instances    evidently    accumulated  J 
beneath    the   ice    as  a  "ground  moraine."      These   low  spaces  between 
well-defined  terminal  moraines  are  frequently  occupied  by  lakes  or  bv  | 
grassy  meadows,  and  furnish  some  of   the  most  charming  features   of 
mountain  scenery. 

Morainal  Embankments.  —  When  a   glacier   is    prolonged   bey o] id  ^ 
the    entrance    of   a   mountain  valley  and   reaches  an  adjacent  plain,  it^P"^'*^' 


INTUODUCTION. 


28 


may  expand  and  end  in  a  semicircular  ice  foot,  or  preserve  its  stream- 
like form  and  finally  melt  without  expanding  laterally.  The  marked 
contrast  in  the  behavior  of  different  glaciers  in  this  respect  depends  on 
the  relative  abundance  of  d<5bris  in  their  lateral  and  in  their  ten:iinal 
moraines.  When  the  debris  on  the  margins  of  a  glacier  is  small  in 
volume,  the  ice  has  freedom  to  expand  on  getting  Tree  from  the  valley 
through  which  it  descended,  but  when  the  margins  of  the  prolonged 
stream  are  more  heavily  charged  with  debris  than  its  extremity,  lateral 
exi)ansion  is  checked,  while  the  clear  ice  at  the  extremity  flows  on. 
The  ice  advances  between  the  stagnant  bordera  of  the  stream  to  a  greater 
or  less  distance,  depending  upon  the  supply  from  the  higher  mountains  ; 
and  when  it  retreats,  the  heavy  lateral  moraines  are  left  as  parallel 
ridges  with  steep  slopes  on  each  side.  These  ridges  frequently 
resemble  great  railroad  embankments.  The  best  examples  of  structures 
of  this  character  that  have  been  described  are  situated  at  the  east  base 
of  the  Sierra  Nevada,  in  Mono  valley,  California.^  Their  general  appear- 
ance is  shown  in  Plate  4. 

Morainal  embankments,  like  lateral  moraines  on  the  sides  of  a  valley, 
may  be  united  by  terminal  moraines  so  as  to  form  lake  basins.  When 
the  terminal  moraines  are  composed  of  coai-se  material  and  are  too 
open  to  retain  water,  or  when  they  have  been  breached  by  overflowing 
streams,  grassy  meadows  and  forest-covered  parks,  frequently  of  great 
;  beauty,  occupy  the  spaces  between  them  wliicli  were  formerly  fiUeu  by 
[the  retreating  ice  stream. 

Frontal    Moraines.  —  Moraines    left   by  piedmont   and    continental 

j  glaciei"s  are  of  the  same  general  character  as  those  deposited  by  alpine 

glaciers,  but  are  frequently  of  vast  extent.     The  frontal   moraines   of 

continental    glaciers    corresponding    to   the  terminal   moraines  of   local 

ice  streams,  are  in  some  instances  a  score  or  more  of  miles  broad  and 

not  only  hundreds  but  thousands  of    miles  long.     Where  two  lol)es  of 

[a  continental    glacier   come  together  *heir  frontal   moraines  are  united 

[and  form  what    is    known    as  an  interlohate  moraine.     The  best  known 

lexaraples  are  in  the  upper  Mississippi  valley,  and  mark  the  junction  of 

Ithe  larger  marginal  extensions,  or  lobes,  of  the  Pleistocene  ice  sheet  of 

phat  region. 

1"  Quaternary  History  of  Mono  Valley,  California,"  8th  Annual  Report,  U.  S.  Geo- 
logical Survey,  pp.  300-368,  Pis.  35,  30. 


f    _ 


"I^W 


24 


GLACIERS    OP    NORTH    AMERICA. 


Till.  —  Besides  the  irregular  piles  and  ridges  of  unassorted  d^bns 
composing  the  moraines  formed  about  the  margins  of  glaciers,  there 
are  accumulations  of  clay,  filled  at  times  with  stones  and  boulders, 
which  are  deposited  l)eneath  the  ice  during  its  advance,  and  fortn  what 
are  frequently  termed  ground  moraines.  This  material  is  widely  spread 
over  formerly  glaciated  regions,  and  is  now  generally  designated  by  the 
Scottish  name  till,  and  is  less  frequently  spoken  of  as  boulder  clay. 
The  term  boulder  clay,  however,  has  been  given  a  somewhat  different 
meaning  by  a  few  authors. 

The  characteristics  of  till  aro  its  compactness,  due  to  the  pressure 
to  which  it  was  subjected  beneath  the  ice,  and  the  worn  and  striated 
condition  of  many  of  the  pebbles  and  bouldera  scattered  irregularly 
through  it.  As  till  was  not  exposed  to  the  atmosphere  during  its  de- 
position, and,  on  account  of  its  compactness,  is  impervious  to  surface 
waters,  the  material  of  which  it  is  composed  is  in  an  unweathered 
condition  and  frequently  of  a  bluish  color,  owing  to  the  fact  that  the 
iron  contained  in  it  has  not  been  oxidized.  Its  unweathered  condition 
is  in  marked  contrast  to  the  surface  moraines  of  many  glaciers  and  to  | 
ancient  glacial  deposits  which  have  been  long  exposed  to  the  atmosphere. 


I 


Drumliiis.  —  The  abandoned  paths  of  great  glaciers  are  sometimes 
marked  by  smooth,  oval  hills  that  are  lenticular  in  horizontal  sections 
and  have  their  longer  axes  parallel  to  the  movement  of  the  ice  which 
formerly  covered  them.  These  peculiar  and  easily  recognized  emi- 
nences are,  in  the  case  of  certain  typical  examples,  about  500  feet  in  I 
least  diameter,  with  a  length  of  from  1500  to  2000  fee,  and  a  maxi- 
mum height  of  from  50  to  150  feet.  They  exhibit  many  variations  in 
tize  and  shape,  however,  some  being  nearly  circular,  mammillary  hilh. 
and  othera  lenticular  hills,  in  which  the  longer  axis  is  two  or  three 
times  as  great  as  the  shorter  axis.  In  some  instances  they  form  narrow 
ridges  several  miles  in  length.  The  beautiful  curves  formed  by  their 
crests  when  seen  from  the  side,  is  illustrated  by  the  outline  of  a  typi-  ^ 
cal  example  near  Groton,  Mass.,  here  presented.  They  occur  at  all 
elevations  from  s;a  level,  and  even  below  that  horizon,  to  1500  feet  or  | 
more  above  tide,  and  are  found  on  uneven,  rocky  ground  as  well  as  on 
smooth  plains.  They  are  composed  of  compact  till  which  is  frequently 
laminated,  and  seldom  exhibit  evidences  of  stratification  or  other  wattr 
action.  Boulders  and  large  angular  stones  occur  within  their  mass,  and 
scattered  over  their  surfaces.     These  peculiar  hills,  for  which  the  Irisli 


ii 


INTRODUCTION. 


25 


term  drumlin  is  now  gjiiemlly  adopted,  have  been  studied  especially 
near  lioston,  and  occur  also  in  many  other  parts  of  New  England. 
They  are  abundant  in  the  upper  portion  of  the  Huflson  Kiver  valley, 
in  centiul  New  York,  and  have  been  reported  from  Michigan  and  Wis- 
consin. In  general  they  are  situated  well  within  the  terminal  moraine 
which  marks  the  southern  limit  of  the  last  ice  invasion  of  northeastern 
North  America.     Many  diundins  in  the  Connecticut  and    Hudson  val- 


Pio.  2.  —  DRUHLnr  nbab  Groton,  Mass.    After  Frvk. 

leys,  and  other  similar  regions,  are  partially  or  wholly  buried  beneath 
Champlain  clays,  which  were  deposited  during  a  time  of  land  depres- 
sion immediately  after  the  last  recession  of  the  ice.  Thus  far,  drumlins 
have  not  been  observed  in  connection  with  existing  glaciers.  This  is 
due,  perhaps,  to  the  fact  that  they  are  not  known  to  originate  beneath 
glaciers  of  the  alpine  type,  and  also  because  they  seem  to  be  a  phase 
of  the  l)t'havior  of  the  somewhat  central  portions  of  large  ice  sheets,  and 
are  only  open  to  view  when  the  ice  has  withdrawn. 

The  characteristic  whahhack  shape  of  drumlins,  the  compactness 
and  frequent  lamination  of  the  till  composing  them,  as  well  as  other 
facts  in  connection  with  their  composition  and  distribution,  have  led  to 
the  generally  adopted  conclusion  that  they  were  formed  beneath  moving 
ice  sheets.  Various  hypotheses  have  been  proposed  to  explain  their 
origin,  but  thus  far  opinion  is  divided  in  reference  to  the  precise  man- 
ner of  their  formation. ^ 

Without  attempting  to  present  a  review  of  the  various  hypotheses  that 
have  been  advanced  in  reference  to  the  origin  of  drumlins,  I  venture  to 
suggest  that  the  effect  of  debris  on  the  flow  of  ice  enclosing  it  may  fur- 
nish the  desired  explanation. 

The  presence  of  debris,  i.e.  boulders,  stones,  sand,  dirt,  etc.,  in  glacial 
ice,  increases  its  resistance  to  motion,  as  will  be  more  fully  discussed  in 

^  A  discussion  of  the  origin  of  draralins,  by  Warren  Upham,  containing  references  to  pre- 
vious papers  on  the  same  subject,  may  be  found  in  the  Proceedings  of  the  Boston  Society  of 
Natural  History,  vol.  26,  1892,  pp.  2-17. 


Y^ 


V.6 


OLACIKlta   OF   NORTH   AMERICA. 


;i  I. 


li  ! 


; 


advance.  I)6hriH  included  in  ic^e  may  Ih)  said  to  .stiffen  it  and  to  decreiiHe 
its  pljiHticity  ;  or,  in  other  wonls,  increase  its  reHiHtiince  to  forces  tendinpr 
to  shear  it.  With  this  principle  in  mind,  we  are  led  to  conclude  that  if  a 
mass  of  d^hris  is  inchuhfd  in  a  fjfhicier,  motion  in  the  debris-charged  mass 
will  be  retarded,  ond  the  adjacent  clear  ice  will  flow  around  it.  When  the 
debris  reaches  a  >;!ertain  proportion,  varying  with  conditions,  motion  will 
cease,  and  if  the  rate  of  flow  of  the  clear  ice  does  not  increase,  the  ddbris- 
charged  niiuss  will  remain  stagnant.  If  the  debris  is  most  abundant  about 
a  central  nucleus,  and  becomes  less  and  less  abundant  in  all  directions 
from  the  nucleus,  the  flow  of  the  ice  will  be  least  in  the  center,  or  if  the 
debris  is  there  suthciently  abundant,  will  remain  stagnant,  while  motion 
in  adjacent  portions  will  increase  in  a  definite  ratio  until  the  normal  flow 
of  clear  ice  under  given  conditions  is  reached.  If  a  nucleus  of  debris,  as 
above  postulated,  is  situated  in  the  central  part  of  a  glacier,  with  clear  ice 
beneath,  it  may  behave  like  a  boulder  and  be  carried  bodily  forward  ;  but 
if  situated  at  the  bottom  it  will  retain  its  position,  and  the  clear  ice  will 
flow  over  it.  If  the  ice  flowing  past  the  stagnant  maas  has  earth  and 
stones  scattered  through  it,  the  d6bris  reaching  the  nucleus  will  Ije 
retarded  and  the  clear  ice  flow  on.  The  nucleus  of  debris  would  thus 
receive  additions  and  be  compacted  and  moulded  by  the  clear  ice,  or  ice 
but  moderately  charged  with  foreign  matter,  flowing  past  it.  A  shape 
presenting  least  resistance  to  llie  flowing  ice  would  thus  be  acquired, 
and  the  longer  axis  of  the  stagnant  mass  would  be  parallel  with  the 
direction  of  glacial  flow.  Under  this  conception  of  the  growth  of 
drumlins,  the  fact  that  they  frequently,  and  possibly  normally,  contain 
debris  that  has  been  derived  from  lower  levels  presents  no  difficulty, 
since  ice  under  pressure  behaves  as  a  viscous  fluid,  and  will  flow  in 
the  direction  of  I'^^st  resistance.  If  the  resistance  at  the  sides  of  a 
stagnant  nucleus  y^-kf  greater  than  over  its  summit,  the  approaching  ice 
would  rise  and  ii-w  over  the  oKstruction,  carrying  with  it  the  debris 
contained  wilhin  its  mass.  The  varying  forms  of  drumlins,  the  fact  that 
they  sometin.es  cover  a  nucleus  of  rock-in-place,  their  laminated  structure, 
remarkable  compactness,  and  general  flowing  outlines,  all  seem  to  harmo- 
nize with  the  view  of  their  origin  here  suggested. 

Certain  drumlins  of  what  may  be  termed  the  New  York  type,  i.e.  those 
that  are  greatly  elongated,  are  not  symmetric,  but  their  ends  in  the  direc- 
tion from  which  the  ice  came  which  moulded  them  into  shape  are  moder- 
ately broader  and  more  blunt  than  the  opposite  extremities.  These  elon- 
gated hills  may  be  said  to  have  the  shape  of  half  a  cigar  cut  lengthwise. 


INTUODUCTION. 


27 


il».e  larger  end  of  the  cigar  pointing  in  the  direction  from  which  the  ice 
ciinie,  which  formerly  covered  the  region  where  they  occur.  The  sidcH 
of  these  hills,  an  in  common  with  all  elliptical  or  elongated  drumlins,  are 
more  precipitous  than  the  terminal  .sloj)eH.  On  the  larger  or  proximal 
end8,of  Heveral  cigar-Mhaped  drumlins  observed  by  the  writer  in  Wash- 
ington county,  New  York,  there  is  a  noticeable  increase  in  the  nundn'r 
of  l)oulders  scattered  over  the  surface,  while  at  their  tapering  or  distal 
extremities.  Hue  debris  greatly  piodominates,  and  is  noticeable  Ixjyond, 
where  the  slope  of  the  hills  is  lost.  In  these' examples,  coarae  debris 
seems  to  haye  Ixien  deposited  on  the  enlarged  proximal  ends,  while 
the  sides  and  distal  portion  suffered  erosion,  which  removed  the  larger 
stones. 

Under  the  hypothesis  here  proposed,  drumlins  are  considered  to  have 
grown  by  the  accumulation  of  debris  about  a  centnd  nucleus  either  of 
solid  rock  or  of  ice  charged  with  stones  to  such  a  degree  as  to  increase 
its  resistance  above  the  shearing  forces  brought  to  bear  upon  it;  the  added 
material  being  derived  from  the  ice  which  flowed  past  it.  The  location 
of  a  drumlin  would  be  determined  by  the  presence  of  debris  sufficiently 
abundant  to  cause  stagnation  in  the  ice  containing  it,  which  would  vary 
with  the  rate  at  Avhich  the  ice  moved.  When  the  ice  contained  but  little 
debris  it  might  all  l)e  carried  forward  ;  when  the  debris  was  in  excess,  it 
might  be  left  in  a  general  sheet,  without  special  form.  The  most  favor- 
able conditions  would  be  when  certain  threads,  so  to  speak,  of  the  ice 
current  were  lightly  charged  with  debris,  which  on  account  of  changes 
in  the  contour  of  the  land  over  which  the  ice  flowed,  or  variations  in 
velocity  due  to  other  causes,  would  become  sufficiently  abundant  at  cer- 
tain localities  to  check  the  flow  of  the  debris-charged  ice  and  cause  it  to 
become  stagnant.  The  ice  current  would  then  add  fresh  debris  to  the 
stagnant  nucleus,  and  a  drumlin  representing  the  excess  of  deposition 
over  erosion  would  result. 

The  hypothesis  outlined  above  has  not  been  subjected  to  severe  tests, 
and  is  introduced  here  in  the  hope  that  it  v  ill  stimulate  the  student  to 
make  observations  in  the  field,  which  will  either  sustain  it  or  lead  to  its 
modification  or  rejection.  In  the  study  of  the  origin  of  topographic 
forms,  many  trial  hypotheses  have  to  be  introduced  and  their  value 
tested,  in  order  to  arrive  at  a  true  explanation.  The  above  may  be 
considered  an  example  of  such  a  working  hypothesis.  It  is  the  duty 
of  the  compiler  to  take  his  reader  as  far  as  present  knowledge  seems 
to  warrant,  and  to  point  the  way  into  the  unexplored  country  beyond. 


^ww 


28 


GLACIERS   OP   NORTH   AMERICA. 


I  trust  this  little  excursion  beyond  generally  accepted  conclusions  will 
encourage  the  student  to  continue  the  investigation. 


il  I 


Glacial  SEDiMENrs. 

Deposits  made  by  streams  while  yet  confined  by  glacial  ice,  and  for 
some  distance  after  escaping  from  its  borders,  may  for  convenience  be 
termed  glacinl  sediments^  in  distinction  from  glacial  deposits  made 
directly  from  the  ice  and  classified  as  moraines,  till,  drumhns,  etc. 
These  fluvio-glacial  sediments  are  characterized  by  the  worn  and 
rounded  condition  of  the  aand,  pebbles,  and  boulders  composing  them, 
and  also  by  their  moie  or  less  perfect  stratification ;  while  glacial 
deposits  are,  in  the  majority  of  instances,  composed  of  unassorted, 
angular  debris.  Glacial  sediments  are  in  reality  stream  deposits  made 
under  peculiar  conditions,  determined  by  the  presence  of  land  ice.  For 
this  reason,  they  are  of  greatest  interest  when  studied  in  connection  with 
other  glacial  phenomena.  The  deposits  here  referred  to  are  designated  in 
many  geological  books,  some  of  them  of  recent  date,  as  modified  drift ; 
the  early  supposition  on  which  this  term  is  based  being  that  they  consist 
of  glacial  deposits  that  have  been  worked  over  and  modified  by  streams. 
The  leading  characteristics  of  some  of  the  bestrdefined  deposits  made  by 
glacial  streams  are  briefly  described  below. 

Osars.  —  In  formerly  glaciated  regions  there  are,  in  certain  instances, 
long,  gently  curving,  and  sometimes  tortuous  ridges,  trending  with  the 
direction  of  former  ice  movement,  and  composed  of  water-worn  sand 
and  gravel.  When  their  internal  structure  is  exposed,  they  exhibit 
more  or  less  well-<lefined  cross-bedding  or  oblique  stratification,  pro- 
duced by  rapid  water  currents  :  and  on  their  surfaces  large,  angular 
boulders  are  frequently  to  L,  observed.  Ridges  of  this  chai'acter,  some- 
times 50  to  150  feet  or  more  in  height,  and  perhaps  scores  of  miles  in 
length,  have  been  named  osars,  and  are  believed  to  have  been  formed 
by  streams  flowing  in  channels  beneath  ice  sheets.  The  large,  angu- 
lar stones  resting  on  them  are  of  the  same  origin  as  the  similar  bouldei's 
on  the  surface  of  drumlins  already  referred  to,  and  were  deposited  when 
the  ice  in  which  the  osars  were  formed  was  melted. 

Karnes.  —  Other  accumulations  of  water-worn  sand  and  gravel,  depos- 
ited beneath  glaciers  or  about  their  immediate  margins,  have  irregular 
shapes  and  form  hills  and  knolls  with  undrained  basins  between.     These 


! 


INTRODUCTION. 


29 


lusions  will 


peculiar  and  frequently  very  picturesque  topographic  forms  are  known  as 
kames.  They  are  believed  to  owe  their  origin  to  the  drainage  of  glacieir, 
and  to  have  been  formed  by  the  deposition  of  gravel  and  sand  in  cavities 
beneath  the  ice,  or  after  being  swept  out  from  ice  sheets  by  the  streams 
flowing  from  them  and  dropped  in  open  channels  in  their  margins. 
These  are  the  most  common  of  topographic  forms  composed  of  glacial  sedi- 
ments, and,  like  osars,  frequently  have  large,  angular  blocks  of  rock  scat- 
tered over  their  surfaces,  and  are  sometimes  completely  coated  with  what 
was  at  one  time  englacial  or  superglacial  material.  They  differ  from  osare 
in  the  fact  that  they  form  inegular  hills  with  basins  between,  instead  of 
long,  winding  ridges ;  and  are  distinguished  from  drumlins,  since  they  are 
comi)Osed  of  water- worn  sand  and  gravel,  instead  of  till,  and  differ  in 
their  outlines.  Their  distinguishing  characteristics  are,  especially,  t'.e 
irregularity  and  frequent  changes  in  the  character  of  the  layers  of  which 
they  are  composed,  their  knob  and  basin  topography,  and  the  tact  that  in 
general  they  trend  at  right  angles  to  the  direction  of  movement  in  the  ice 
sheet  to  which  they  owe  their  origin. 


Sand  and  Gravel  Plains.  —  About  the  margins  of  regions  formerly 
covered  by  ice  sheets  and  associated  with  osars  and  kames,  there  are 
frequently  broad  plains  composed  of  irregularly  strat!  'led  sand  and  gravel. 
These  are  the  deposits  made  by  overloaded  glacial  streams  on  emerging 
from  restricted  channels  in  the  ice  and  expanding  and  dividing  into  many 
branches,  and  consequently  dropping  a  large  part  of  their  loads,  or  flowing 
inu;  lakes  where  their  sediments  were  deposited. 

The  formation  of  sand  and  gravel  plains,  both  by  subdividing  streams 
and  in  bodies  of  still  water,  may  now  be  seen  m  progress  about  many 
glaciers.  Conspicuous  examples  occur  at  the  extremities  and  along  the 
borders  of  several  glaciers  in  Alaska.  About  Norris  glacier  in  Taku  inlet, 
shown  in  Plate  11,  there  are  large  deposits  of  sand,  forming  a  low, 
gently  sloping  plain,  across  which  the  feeding  stream  divides  into  many 
distributaries.  Other  deposits  of  this  same  general  character  will  be 
mentiou'id  in  advance  in  describing  the  Malaspina  ice  sheet. 

Abundant  examples  of  the  deposits  referred  to  above  occur  in  the 
region  occupied  by  morainal  material  in  the  northeastern  part  of  North 
America,  and  also  for  many  miles  southward  from  the  southenx  limit 
reached  by  the  ice  during  what  is  generally  termed  the  Second  Glacial 
epoch.  Plains  of  sand  and  gravel,  either  formed  in  small  lakes  and  having 
horizontal  f  arfaces,  or  laid  dov/n  by  bifurcating  streams  and  having  gently 


I 


80 


GLACIERS   OF   NORTH   AMERICA. 


1       ::iili:! 


sloping  surfaces,  make  up  a  very  large  portion,  and  perhaps  ihe  major 
part,  of  glacial  deposits  over  great  areas  in  the  region  of  the  Laurentian 
lakes.  At  times  these  plains  are  marked  by  depressions,  frequently  rudely 
circular  in  outline,  with  steep  banks  of  gravel  and  sand,  and  in  such  in- 
stances have  acquired  the  name  of  pitted  plains.  The  pits  dotting  their 
surfaces,  and  forming  a  marked  chamcteristic  of  their  topography,  are 
believed  to  have  been  formed  by  the  melting  of  isolated  ice  bodies  which 
were  surrounded  or  perhaps  deeply  buried  by  the  gravel  and  sand  during 
the  last  retreat  of  the  glaciera. 


W 


Changes  in  Topography  Produced  by  Glaciers. 

Glaciers  have  a  twofold  and  opposite  effect  upon  the  relief  of  the 
regions  they  occupy.  The  abrasion  produced  by  moving  ice  masses  tends 
to  reduce  and  smooth  out  inequalities,  cut  away  prominences,  and,  as  a 
minor  feature,  excavate  rock  basins.  The  deposits  foi  (Tied  nrlaciers,  either 
directly  or  through  the  agency  of  streams,  in  many  Oi.aCo  ^iii  up  and  level 
off  previously  formed  depressions,  but  in  other  instances,  especially  during 
retreat,  tend  to  accent  the  relief  of  the  surface  and  produce  inequalities. 
The  debris  carried  by  ice  streams  and  by  ice  sheets  is  left  in  confused 
heaps  when  melting  takes  place,  and  produces  well  characterized  topo- 
graphic forms.  Frequently  these  deposits  cover  immense  regions,  and 
are  striking  in  appearance,  and  vary  abruptly  in  relief.  The  sediments  of 
glaciers,  and  particu]  \rly  the  fine  debris  washed  from  them  by  outflowing 
water,  fill  inequalities,  and  on  the  whole,  except  in  the  case  of  osars  and 
similar  accumulations,  tend  to  subdue  and  make  uniform  previous 
inequalities  of  the  land. 

About  the  margins  of  existing  glaciers  that  are  retreating,  ■  >  are 
barren  areas  in  which  the  topographic  forms  peculiar  to  glacia!  i,*  re 

well  displayed.  In  such  instances  one  finds  tumultuous  piles  of  eay;  "  lud 
stones,  now  rising  into  knolls  and  steep-sided  hills,  and,  again,  sinking  into 
dales  and  sand  plains  with  but  little  variation  in  the  surface  contours. 
One  of  the  most  striking  features  in  these  fresh  morainal  deposits  is  the 
presence  of  many  depressions  without  surface  outlets  and  very  frequently 
containing  lakes.     The  drainage  is  markedly  immature. 

On  old  moraine-covered  areas  the  ruggedness  is  commonly  concealed 
somewhat  by  vegetation,  and  many  of  the  lakes  that  formerly  existed  in 
the  depressions  are  transformed  into  bogs  and  grassy  meadowt.  Streams 
originating  in  such  areas   cut   channels  for   themselves  and  tend  still 


INTRODUCTION. 


31 


further  to  drain  the  land.  As  time  goes  on,  a  well-developed  drainage 
system  is  established.  The  lakes  disappear,  and  the  work  of  the  streams 
in  reducing  the  country  to  base  level,  i.e.  the  level  of  standing  water  into 
which  they  discharge,  is  carried  forward  much  the  same  as  in  regions  that 
have  not  been  affected  by  glacial  action.  This  task  is  frequently  greatly 
delayed,  on  account  of  the  climatic  conditions  and  for  the  reason,  also, 
that  glacial  deposits,  especially  osars,  kames,  etc.,  composed  of  unconsoli- 
dated gravel  and  sand,  are^ufficiently  porous  to  absorb  the  rain  water  that 
falls  upon  them  and  allow  it  to  percolate  slowly  f^way,  thus  robbing  it  of 
its  power  to  erode.  The  most  prominent  relief  of  glaciated  lands  is  fre- 
quently such  18  is  produced  by  open,  porous  deposits  of  the  nature  of 
kames  and  osars.  These  retain  their  primitive  form,  while  mountains  of 
indurated  rock  yield  to  the  forces  of  the  atmosphere  and  are  sculptured 
in  various  ways. 

The  most  pronounced  topographic  evidences  of  the  former  presence  of 
an  ice  sheet  are  irregular  moraines  ;  undrained  basins ;  numerous  lakes  , 
long,  winding  gravel  ridges,  or  osars  ;  tumultous  hills  of  gravel,  or  kames  ; 
lenticular  hills  of  till  with  smooth  surfaces,  or  drumlins  ;  broad  and 
frequently  gently  sloping  gravel  plains,  sometimes  with  pitted  surfaces  ; 
boulders,  occasionally  perched  on  hilltops  and  mountain  sides  ;  faceted 
and  striated  stones  ;  outcrops  with  smooth  and  rounded  contoui-s,  and 
polished  and  striated  surfaces. 

With  ihis  elementary  discussion  of  the  general  characteristics  of 
glaciers  and  of  the  records  they  leave  when  climatic  changes  lead  to  their 
disappearance,  we  will  pass  in  the  following  chapters  to  an  account  of  the 
glaciers  now  in  existence  in  North  Ambrica. 


; 


i 


CHAPTER   II. 

GENERAL    DISTRIBUTION    OP    THE    GLACIERS    OF 

NORTH    AMERICA. 

The  glaciers  of  North  America  are  confined  to  the  Cordilleran 
mountain  series  and  to  the  Greenland  region. 

Cordilleran  Reg-ion.  —  The  Cordilleran  series  is,  in  fact,  a  family  of 
mountain  systems  in  most  of  which  there  are  several  independent  ranges 
and  multitudes  of  individual  peaks.  It  is  the  longest  mountain  series  in 
the  world,  extending  as  it  does  from  Cape  Horn  to  the  western  extremity 
of  the  Aleutian  islands,  a  distance  of  over  7000  miles.  In  Central 
America  it  is  represented  by  a  single  system,  in  Mexico  it  becomes  divided, 
and  in  the  United  States  it  is  definitely  separated  into  the  Rocky  mountains. 
Sierra  Nevada-Cascade,  and  Coast  systems.  In  Canada  the  breadth  of  the 
series  increases  northward,  and  four  well-defined  mountain  systems  are 
recognized,  viz. :  the  Rocky,  Gold,  Coast,  and  Vancouver.  What  is  known 
as  the  Coast  range  in  Canada  is  not  a  continuation  of  the  Cascade  mount- 
ains, as  sometimes  stated,  but  is  distinct  from  them  both  topographically 
and  geologically.  Vancouver  system  may  sound  strange  to  many  readers, 
but  is  an  appropriate  designation,  proposed  by  the  Geological  Survey  of 
Canada,  for  the  great  system  of  uplifts  beginning  at  the  south  in  the 
Olympic  mountains,  Washington,  and  extending  northward  through 
Vancouver  and  Queen  Charlo^^te  islands,  and  attaining  its  greatest 
development  on  the  coast  in  southern  Alaska,  and  finally  terminating 
at  the  west  in  the  Aleutian  islands.^ 

In  Canada  and  Alaska  the  mountains  of  the  Cordilleran  series  near 
the  coast  become  more  elevated  than  those  of  the  interior  and  bend 
abruptly  westward  in  the  central  part  of  their  course.  The  eastern 
system  in  the  same  series  is  prolonged  northward,  and  judging  from  the 
meagre  information  at  hand,  decreases  in  height  and  ends  indefinitely 
before  reaching  the  shores  of  the  Arctic  ocean. 

1  A.  R.  C.  Selwyn  and  G.  M.  Dawson,  "  Descriptive  Sketch,  Geological  and  Geographic, 
of  the  Dominion  of  Canada,"  Montreal,  1884,  p.  35. 


DISTRIBUTION  OF  THE  GLACIERS   OF   NORTH   AMERICA. 


83 


Several  of  the  great  volcanic  peaks  of  Mexico,  which  belong  with  the 
Cordilleran  series  but  are  of  secondary  origin,  attain  an  elevation  of  from 
17,000  to  over  18,000  feet,  a.*vl  leach  the  horizon  of  perpetual  snow.  In 
some  instances  true  glaciers  of  small  size  are  ::aid  to  exist  about  their 
summits,  but  little  if  dny  reliable  information  is  available  concerning 
them,  however,  and  we  are  obliged  to  pass  them  by. 

The  southern  limit  of  glaciers  in  the  United  States  is  in  the  High 
Sieri-a,  California,  in  about  latitude  39°.  The  ice  bodies  of  that  region 
are  small,  but  have  many  of  tlie  essential  features  of  the  most  typical 
ice  streams  of  the  alpine  type.  They  are  confined  to  sheltered  amphi- 
theatres about  the  highest  peaks,  and  do  not  extend  l'>wer  than  about 
13,000  or  12,000  feet  above  the  sea.  In  most  instances  they  are  at 
the  northern  base  of  sheltering  precipices,  and  terminate  before  reaching 
the  upper  limit  of  timber  growth. 

In  northern  California,  and  in  Oregon  and  Washington,  glaciers  are 
more  numerous,  of  greater  extent,  and  reach  lower  limits  than  in  the 
Sierra  Nevada,  but  are  still  confined  to  the  higher  portions  of  the  more 
elevated  peaks  and  do  not  extend  to  a  lower  horizon  than  about  6000 
feet  above  the  sea.  In  many  instances  they  reach  the  upper  limit  of  forest 
growth.  The  best  examples  cluster  about  the  summits  of  Mount  Shasta, 
Mount  Rainier  (Tacoma),  Mount  Baker,  and  other  volcanic  peaks  of  the 
same  region. 

In  the  Rocky  mountains,  glaciers  are  foreshadowed  at  the  south  by 
small  snow  bodies  in  Colorado,  which  certain  travelers  who  have  examined 
them  consider  worthy  of  being  numlgred  among  glaciers.^  Perennial 
snow  banks  increase  in  number  and  in  extent  towards  the  north,  and  true 
glaciers  occur  in  Montana  and  adjacent  portions  of  Canada. 

Glaciers  are  numerous  in  the  Cordilleran  series  in  Canada  and  furnish 
some  of  the  most  attractive  features  in  the  scenery  of  that  Wild  and 
picturesque  land,  but  unfortunately  only  meagre  information  concerning 
them  is  yet  available.  The  best  known  examples  appear  in  the  Selkirk 
mountains,  one  of  the  loftiest  ranges  in  the  Gold  system,  and  in  the 
Coast  mountains  in  the  vicinity  of  the  Stikine  river.  Further  north,  in 
the  same  great  mountain  series,  bodies  of  perennial  ice  become  more  and 
more  numerous,  at  the  same  time  increasing  in  size,  and  reach  their 


Geographic. 


1  F.  H.  Chapin,  "The  First  Ascent  of  a  Glacier  in  Colorado,"  Appalachia,  vol.  6,  1887, 
pp.  1-12. 

An  account  of  the  occurrence  of  typical  glaciers  near  McDonald  lake,  in  northern 
Montana,  by  L.  W.  Chaney,  Jr.,  was  published  in  Science,  vol.  2,  1896,  pp.  792-706. 


84 


GLACIERS   OF   NOlilH   AMEUICA. 


I'^iii  m 


most  magnificent  development  in  southern  Alaska.  The  most  thoroughly 
ice-covered  region  in  the  Cordiileran  series  is  in  tne  vicinity  of  Mounts 
Fairweather,  Logan,  and  St.  Elias,  and  lies  partially  in  Alaska  and 
partially  in  Canada.  Westward  from  that  stronghold  of  perennial 
ice,  as  previously  stated,  the  mountains  decrease  in  elevation.  The 
effec".  of  this  change,  and  probably  also  of  accompanying  variations 
in  climatic  conditions,  is  seen  in  the  glaciers,  which  become  smaller  and 
more  widely  separated  and  are  confined  to  higher  and  higher  regions 
when  traced  westward  t  >  the  Alaska  peninsula  and  the  Aleutian  islands. 

As  one  follows  the  great  Cordiileran  glacial  belt  northward  from  its 
first  appearance  in  the  High  Sierra,  the  lower  limit  of  perennial  snow,  or  the 
"snow  line,"  at  first  about  12,000  feet  above  the  sea,  descends  lower  and 
lower,  until  finally  in  the  vicinity  of  Mount  St.  Elias  it  has  an  elevation 
of  only  2000  or  2500  feet.  Farther  west,  along  the  curve  made  by  the 
mountains  about  the  northern  shore  of  the  Pacific,  the  snow  line  again 
rises,  and  on  the  Aleutian  islands  has  an  elevation  of  perhaps  8000  or 
10,000  feet.  The  glacial  ice  everywhere  extends  below  the  limit  of  peren- 
nial, n6v6  snow,  but  is  most  thoroughly  exposed  in  late  summer  or  early 
autumn,  when  the  true  position  of  the  snow  line  is  sharply  defined.  In 
the  High  Sierra,  the  extension  of  glacial  ice  below  the  neves  is  but  slight, 
and  during  seasons  of  unusual  snowfall,  or  when  the  summei-s  are  excep- 
tionally cool,  may  not  be  recognizable.  Proceeding  northward,  the  ice 
extension  is  more  and  more  pronounced,  until  the  region  of  maximum 
glaciation  is  reached.  Thence  westward  the  length  of  the  tongues  of  ice 
below  the  snow  fields  decreases. 

In  the  High  Sierra,  as  already  stated,  the  glaciers  do  not  descend 
below  about  12,000  feet ;  farther  north  they  reach  lower  and  lower  limits, 
until  in  the  vicinity  of  Stikine  river,  in  about  latitude  67°,  they  gain  the 
sea  level.  Thence  northward  and  westward  to  beyond  Mount  St.  Elias,  a 
distance  along  the  coast  of  between  700  and  800  miles,  there  are 
hundreds  and  probably  thousands  of  glaciers  that  descend  practically  to 
sea  level,  and  scores  that  enter  the  sea  and,  breaking  off,  form  bergs. 
Beyond  the  Mount  St.  Elias  region  their  lower  limit  gradually  rises. 

At  the  southern  end  of  the  crescent-shaped  belt  of  glaciere  under 
consideration,  the  ice  bodies  are  small  and  detached,  and  are  sepai'ated 
from  each  other  by  intervening  ridges  and  mountain  peaks.  Proceeding 
northward,  they  increase  in  area  and  in  frequency,  and  unite  one  with 
another  in  the  neve  region.  The  snow  belt  broadens  and  finally  becomes 
a  confluent  sheet  80  or  100  miles  broad  in  southern  Alaska,  and  narrows 


DISTKIBUTION    OF   THE   GLACIEUS   OF    NORTH    AMERICA. 


35 


again  westward  and  is  there  broken  into  individual  n^v^s  of  limited 
extent  similar  to  those  of  the  High  Sierra.  The  most  thoroughly  snow 
and  ice-cove»ed  portion  is  in  the  region  between  Lynn  canal  and  Cook's 
inlet,  Alaska,  where  not  less  than  15,000  square  miles  of  mountainous 
country  is  almost  completely  buried  beneath  a  single  vast  nev6  field  from 
which  ice  streams  of  the  alpine  type  flow  both  north  and  south  through 
rugged  defiles  in  the  flanks  of  the  mountains.  The  southward  flowing 
glaciers  are  larger,  more  numerous,  and  much  longer  than  those  that  find 
their  way  northward,  and,  in  gaining  the  low  lands  adjacent  to  the  ocean, 
expand  and  unite  one  with  another,  so  as  to  form  broad  plateaus  of  ice, 
known  as  piedmont  glaciers. 

Could  the  observer  obtain  a  bird's-eye  view  of  the  western  portion  of 
North  America,  he  would  find  that  the  Cordillera'  glaciers  form  an  irreg- 
ular curve,  broadest  and  reaching  sea  level  in  the  Mount  St.  Elias  region, 
and  narrowing  and  becoming  more  and  more  elevated  at  lx)th  its  southern 
and  western  extremities.  The  attenuated  arms  of  this  shining  crescent  are 
broken,  for  the  reason  that  only  the  more  elevated  mountains  near  its 
extremities  -jach  the  horizon  at  which  perennial  snow  exists.  As  in  the 
crescent  of  light  reflected  from  the  surface  of  the  moon,  the  mountains  in 
the  Cordilleran  ice  crescent  where  the  belt  is  broadest  are  white  to  their 
bases,  while  only  the  peaks  of  the  most  lofty  elevations  at  the  extremities 
of  the  broken  circle  are  brilliant.  The  length  of  this  crescent  of  snow 
and  ice  is  about  3000  miles.  Its  form  is  less  regular,  however,  than  the 
comparison  made  above  might  lead  one  to  suppose,  as  its  southern 
prolongation  is  broader  and  more  broken  than  its  central  a^nd  western 
portions. 

The  study  of  the  glaciers  of  the  Cordilleras  has  only  fairly  begun,  but 
it  is  hoped  that  what  has  already  been  accomplished  will  convince  the 
reader  that  the  subject  is  not  only  worthy  of  consideration,  but  of  fascina- 
ting interest,  and  that  the  work  of  exploration  should  be  continued. 

Greenland  Region.  —  In  the  eastern  portion  of  North  America  gla- 
ciere  are  confined  to  Greenland,  and  to  the  islands  adjacent  to  it  on  the 
west.  The  vast  ice  sheet  covering  nearly  all  of  Greenland  is  of  the  contin- 
ental type,  and,  as  is  well  known,  is  the  largest  existing  ice  body  in  the 
northern  hemisphere.  Its  extension  northward  has  not  been  fully  deter- 
mined, but  as  nearly  as  can  be  judged  it  terminates  in  about  latitude 
82  °.  Its  a,vei  is  in  the  neigLoorhood  of  600,000  square  miles.  If 
transferred  bodily  to  the  eastern  portion  of  the  United  States,  it  would 


WF 


86 


GLACIERS   OF   NORTH   AMERICA. 


extend  from  northern  Maine  to  Georgia,  and  cover  a  belt  of  country  500 
miles  broad.  Vast  as  this  ice  8he,.t  is  known  to  be,  it  takes  whit-  may  be 
said  to  be  second  or  third  rank  when  contrasted  with  the  continental 
glaciers  that  occupied  Canada  and  a  large  portion  of  the  United  States  in 
Pleistocene  times.  The  exploration  of  existing  glaciers  derives  one  of  its 
principal  attractions  from  the  fact  that  such  studies  assist  in  interpreting 
the  records  left  by  ancient  glaciers  in  various  parts  of  the  world.  This 
in  turn  brings  one  to  the  consideration  of  the  still  broader  problems  of  the 
cause  of  climatic  changes  which  favored  the  growth  of  vast  Pleistocene 
glaciers  in  regions  now  enjoying  a  temperate  climate,  and  inhabited  by 
the  most  civilized  people  of  the  earth. 

The  glaciers  on  the  islands  to  the  west  of  Greenland  are  but  imper- 
fectly known,  but  from  the  somewhat  meagre  reports  rendered  by  Arctic 
explorers,  few  of  whom,  it  is  to  be  regretted,  have  been  trained  observere  in 
this  direction,  it  appears  that  they  are  of  the  alpine  type,  although  larger, 
and  with  broader  neve  fields  in  proportion  to  the  extent  of  true  glacial 
ics,  than  is  found  among  the  s^laciei's  of  Switzerland  or  other  similar 
regions.  A  remarkable  feature  of  the  glaciers  of  the  far  north  is  that 
they  frequently  terminate  in  bold  precipices  of  ice. 

Having  this  general  sketch  of  the  distribution  of  glaciers  in  North 
America  in  mind,  the  reader  will  be  enabled  to  locate  in  the  outline  plan 
the  relations  of  the  various  ice  bodies  described  in  the  following  chapters. 


CHAPTER  III. 

GLACIERS    OP    THE    SIERRA    NEVADA. ' 

The  Sierra  Nevada,  in  many  respects  the  most  attractive  mountain 
system  in  North  America,  attains  its  greatest  elevation  between  hititude 
30°  and  38°  30',  or  in  a  more  general  way,  between  Owen's  lake  and  Lake 
Tahoe,  California. 


The  High  Sierra. 

To  the  more  elevated  portion  of  the  Sierra  Nevada  the  name  "  High 
Sierra "  has  been  applied.  Although  the  boundaries  of  the  region  thus 
designated  are  indefinite,  it  is  well  worthy  of  especial  recognition,  as  it  is 
a  prominent  and  important  topographic  feature.  Throughout  its  entire 
extent  it  bristles  with  rugged  peaks,  narrow  crests,  and  inaccessible  cliffs, 
overshadowing  profound  chasms,  all  of  which  combine  to  form  one  of  the 
most  rugged  and  picturesque  mountain  ranges  in  North  America.  The 
culminating  point  of  this  elevated  region  is  near  its  southern  limit,  where 
Mount  Whitney  rises  to  an  elevation  of  14,522  feet  above  the  sea,  and  is 
succeeded  northward  by  Mount  King,  Mount  Humphreys,  and  man}'  other 
elevations  scarcely  less  magnificent.  Southward  from  Mount  Whitney  the 
Sierra  declines  rapidly,  and  the  system  is  considered  as  terminating  in  that 
direction  at  Tehichipi  pass,  a  little  north  of  latitude  35°.  Northward  of 
Mount  Whitney,  there  is  a  vast  sea  of  rugged  peaks  and  narrow  moun- 
tain crests,  separated  by  deep  valleys,  which  render  the  region  almost  inac- 
cessible to  beings  not  eqinpped  with  wings.  This  is  the  High  Sierra 
par  excellence^  as  will  be  admitted  by  all  who  attempt  to  scale  its  giddy 
heights  or  thread  its  labyrinth  of  cations.  In  the  neighborhood  of  Mono 
lake  a  number  of  the  more  prominent  peaks,  of  which  Mount  Lyell, 
Mount  Hitter,  Mount  Dana,  and  Tower  peaks  are  examples,  exceed  13,000 
feet  in  elevation.  The  range  retains  its  rugged  character  all  the  way  to 
Sonora  pass,  and  even  to  Lake  Tahoe,  but  northward  of  that  "  Gem  of 
the  Sierra  "  the  mountains  are  less  elevated. 

1  This  account  of  the  glaciers  of  the  Sierra  Nevada  is  taken  almost  entirely  from  a  paper 
I  by  the  present  writer,  on  the  "  Existing  Glaciers  of  the  United  States,"  6th  Annual  Report 
U.  S.  Geological  Survey,  1883-84. 


38 


GLACIERS   OF    NOIITH    AMKUICA. 


vli; 


Very  liirpo  portions  of  tlie  Higli  Sierni  iire  c-omijosed  of  lightrcolored 
granite,  but  thinly  flotlu'd  with  vegetation,  whieh  inii)art8  a  monotonous 
gray  tone  to  the  rugged  scenery.  The  peaks  and  crests  overlo(»king  Moiu* 
lake,  however,  liave  been  sculptured  from  metamorphosed  sedimentary 
rocks,  and  are  frequently  richly  tinted.  The  landscape  in  this  portion 
of  the  range  is  warm  in  tone,  and  presents  pleasing  and  striking  contrasts 
ill  comparison  with  the  gray  of  the  western  slopes.  Hugged  and  angular 
precipices  rising  to  narrow  crests,  hut  softened  in  contour  and  varied  in 
color  on  their  lower  slopes  by  lichens  and  al[)ine  llowers,  dark  billowy 
forests  of  pine  in  the  valleys,  snow-lillcd  am[)hitheatres,  and  hundreds  of 
placid  lakelets  and  rock-rinuncd  tarns  are  there  grouped  in  i)i(,'tures  that 
are  as  delicate  in  detail  and  as  pleasing  in  tone  iw  they  are  majestic  and 
far-reaching.  '  ' 

Besides  the  splendor  of  their  scenery,  the  mountains  to  the  south- 
ward of  Mono  lake  present  the  additional  attraction  of  living  glaciers. 
These,  although  small,  are  well  worthy  the  careful  attention  of  every 
traveler. 

Existing  glaciers  on  Mount  Dana  and  Mount  Lyell  were  visited  by 
Mr.  (t.  K.  Gilbert  and  myself  during  the  sununer  of  1883.  I  also  exam- 
ined one  at  the  head  of  Parker  creek,  a  tributary  of  Mono  lake.  Others 
on  Mounts  Conness,  McClure,  and  Ritter  were  explored  by  Mr.  W.  D. 
Johnson,  my  associate  for  several  years  in  western  explorations,  while 
making  a  topographical  survey  of  the  region  draining  to  Mono  lake. 
Besides  the  glaciers  actually  traversed,  a  number  of  others  were  seen 
from  commanding  points,  and  their  general  nature  almost  as  thoroughly 
determined  as  if  their  surfaces  had  actually  been  trodden.  Our  combined 
observations  show  that  nine  glaciers  exist  within  the  southern  rim  of  the 
Mono  lake  drainage  basin.  A  somewhat  larger  number  are  sheltered  by 
the  mountains,  of  which  the  dominant  peaks  are  McClure,  Lyell,  and 
Hitter.  It  is  in  ice  caves  beneath  these  glaciers  that  the  Tuolumne, 
Merced,  and  San  Joaquin  rivers  have  their  birth. 

The  glaciers  of  the  High  Sierra  are  located  between  latitudes  36"  30' 
and  38°,  ana  at  their  lower  extremities  have  an  approximate  elevation  of 
11,500  feet  above  the  sea.  The  lowest  seen  is  on  the  northern  side  of 
Mount  Ritter,  and  terminates  in  a  lakelet  that  is  about  2000  feet  below 
the  mountain  top,  or  about  11,000  feet  above  the  sea.  The  glaciers 
observed  are  all  small,  the  most  extensive  —  that  on  the  northern  slope 
of  Mount  Lyell — being  less  than  a  mile  in  length,  with  a  somewhat 
gi'eater  breadth.     Nearly  all  occur  in  amphitheatres  on  the  northern  side 


);i,AitKHi«  ">K   N'liHIII    AMKIch.4. 


I'r.  kTK  '.'. 


Fig.   a.  — mount    DANA    GLACIER,   CALIFORNIA. 
( >ii  tli<'  iiortlicrn  «iiU'  "f  the  smiiiiiit-|n'iik  of  .Ml.  I  >iiiiii. 


Fig.   B.— mount    LYELL   GlACIER,   CALIFORNIA. 
The  liiKhest  peak  is  the  sutnmit  of  Mt.  Lyell. 


GLACIERS   OF  THK  SIERRA   NEVADA. 


89 


(if  lofty  peaks,  where  they  are  fiheltored  from  the  iiooiulay  sun  hy  liigh 
cliffs  and  mountain  ridges;  and  all  How  northward,  with  the  exception  of 
a  few  cradled  in  deep  cirques  on  the  eastern  side  of  the  Minarets  and 
Mount  Hitter.  So  far  iis  known,  these  are  the  most  southern  glaciers  in 
the  United  States.  Snow  fields  are  reported  hy  Mr.  Johnson,  however, 
as  existing  in  the  mountains  to  the  south  of  Mount  Hitter,  at  the  head  of 
some  of  the  many  brandies  of  Owen's  river.  If  these  should  pn)ve  to  1k3 
veritable  glaciers,  they  will  extend  the  southern  limits  of  the  existing 
glaciera  of  this  country  a  few  miles  farther  southward. 


Mount  Dana  Glacier. 

On  the  western  shore  of  Mono  lake  the  mountains  rise  abruptly  from 
the  water's  edge  to  an  elevation  of  5000  to  6600  feet,  and  have  Iweii 
sculptured  by  storms  and  frosts  into  indei)endent  peaks  of  remarkable 
giandeur.  As  seen  from  Mono  lake,  the  most  conspicuous  point  along 
the  serrate  mountain  crest  outlined  against  the  western  sky  is  Mount  Dana, 
which  rises  6600  feet  abov«^  the  lake,  and  has  an  elevation  of  12,992  feet 
above  the  sea.  Although  grand  proportions,  this  peak  is  but  one  among 
many  prominent  points  crowning  the  divide  between  the  drainage  of  Mono 
lake  and  the  Pacific.  From  the  southward,  Mount  Dana  presents  a 
somewhat  rounded  contour  and  is  easy  of  ascent,  but  on  the  north  its 
culminating  cliffs  form  a  nearly  perpendicular  precipice  more  than  a 
thousand  feet  high.  This  northern  face  descends  into  a  deep,  narrow 
gorge  leading  northward,  known  as  Glacier  cafion.  During  the  glacial 
epoch  the  whole  extent  of  this  cafion  was  occupied  by  ice,  and  formed  a 
tributary  to  a  still  larger  glacier  flowing  into  Mono  valley. 

At  the  head  of  Glacier  cafion,  and  surrounded  on  nearly  all  sides  by 
towering  precipices,  lies  the  small  ice  body  represented  on  Fig.  A,  Plate 
2,  to  which  the  name  Mount  Dana  glacier  has  been  given.  The  picture 
shows  nearly  the  entire  extent  of  the  glacier,  and  is  from  a  photograph 
taken  on  an  abandoned  terminal  moraine  now  retaining  a  lake  of  opalescent 
water,  into  which  the  drainage  from  the  ice  discharges.  In  the  illustra- 
tion the  terminal  moraine  now  forming  about  the  border  of  the  ice  can  be 
seen,  as  well  as  the  crevasses,  dirt  bands,  etc.,  that  mark  its  surface.  The 
glacier  is  about  2000  feet  long  in  the  direction  of  flow,  but  appears  much 
foreshortened  in  the  illustration.  "  Ice  tongues  "  are  seen  extending  uj>- 
ward  from  the  neve.  At  the  base  of  the  largest  of  these  peculiar  ice 
tributaries  a  portion  of  a  wide  crevasse,  or  bergschrund,  may  be  recognized. 


40 


GLACIERS    OF   NORTH    AMERICA. 


Ill 


This  miniature  glacier  exhibits  many  of  the  essential  features  of  greater 
ice  streams,  such  as  neve  and  glacier  proper,  crevasses,  dirt  bands, 
morpines,  glacier  tables,  etc.,  as  will  be  described  in  connection  with  simi- 
lar features  on  neighboring  ice  bodies  a  few  pages  in  advance. 

Mount   Lyell  Glacier. 

In  traveling  ^rom  Mount  Dana  to  Mount  Lyell,  one  finds  it  most 
convenient  to  pass  down  Dana  creek,  which  flows  southward  from 
Mount  Dana,  to  its  confluence  with  Tuolumne  river,  and  then  ascend 
the  deep,  broad  caflon  of  the  latter  stream.  Tuolumne  river  has  its 
birth  at  the  extremity  of  the  Mount  Lyell  glacier.  It  emerges  from  u 
cavern  in  the  ice  as  an  insignificant,  dirt-laden  brook.  The  snowy 
summit  of  Mount  Lvell,  as  seen  from  the  head  of  Tuolumne  cafion,  is 
shown  in  Plate  3.  The  majestic  mountain,  when  viewed  from  this 
portion  of  the  vp.Uey,  is  far  more  beautiful  than  any  illustration  in 
black  and  while  can  suggest.  In  the  soft,  gray  light  of  morning,  it 
has  all  tile  solemn  grandeur  of  the  Tiernese  Oberland.  At  sunset, 
when  flushed  with  the  rosy  light  of  the  afterglow,  this  shrine  of  the 
High  Sierra  rivals  the  splendor  of  Mount  Rosa,  To  the  right  of  Mount 
Lyell  rises  Mount  McClure,  which  is  scarcely  less  imposing  than  its 
companion;  the  former  attains  the  height  of  13,420  feet  above  the  sea, 
and  the  latter  is  but  150  feet  less  in  elevation. 

The  Tuolumne  cailon,  when  followed  still  nearer  its  beginning,  is  found 
to  lose  its  gentle  grade  and  become  rugged  and  precipitous.  Its  bed  is 
crossed  at  jntervalt^  by  irregular  cliffs,  that  must  have  caused  magnifi- 
cent ice  cascades  in  the  great  glacier  that  once  flowed  over  them.  Tho 
top  of  each  steep  ascent  is  usually  separated  from  the  base  of  the  next 
higher  one  by  a  comparatively  level  tract,  sometimes  holding  a  grassy 
meadow  or  small,  rock-enclosed  tarn.  This  succession  of  cliffs  and 
terraces  forms  a  grand  stairway,  leading  to  the  opening  of  the  amphi- 
theatre on  the  north  side  of  Mount  Lyell,  where  a  magn'ficent  pano- 
rama of  the  entire  glacier  may  be  obtained.  The  view  given  on  Fig. 
E,  Plate  2,  is  from  near  the  outlet  of  the  amphitheatre,  and  exhibits 
nearly  the  whole  extent  of  the  n6ve  of  the  Mount  Lyell  glacier  and 
ol  the  small  area  of  compact  ice  which  projects  from  beneatli  it  In 
the  panorama  the  terminal  moraine  of  dirt  and  stones,  now  forming' 
at  the  foot  of  the  glacier,  may  be  recognized,  and  also  the  rounded 
and  worn  rock  masses  that  rise  as  islands  in  the  central  portion  of  the 


GLACIERS   OF   THE   SIERRA   NEVADA. 


41 


sjlacier.  Crevasses,  contorted  dirt  bands,  and  moraines  on  the  ice, 
although  noticeable  features  when  traversing  its  surface,  are  but  indif- 
ferently shown  m  the  illustmtion. 

Parker  Creek  Glacier. 

This  glacier  is  situated  at  the  head  of  a  deep,  high-grade  caflon,  down 
which  Parker  creek  descentls  on  its  way  to  Mono  lake.  It  is  even  smaller 
than  the  ice  bodies  on  Mount  Dana  and  Mount  Lyell,  but  is  yet  a  true 
glacier  with  a  well-defined  n^v6  region,  from  beneath  which  descends 
a  mass  of  ice  that  is  crossed  by  dirt  bands  and  crevasses,  and  has  many 
minor  features  that  duplicate  the  details  of  more  extensive  ice  streams. 
About  the  lower  margin  of  the  ice  there  are  comparatively  large  moraines 
forming  concentric  ridges,  and  indicating  the  rapid  disintegration  of  the 
surrounding  cliffs,  since  the  material  of  which  they  are  composed  was 
derived  entirely  from  that  source.  The  mass  of  debris  surrounding 
this  glacier  appears  to  exceed  the  volume  of  the  ice  of  which  it  is 
formed.  These  moraines  are  more  characteristic  examples  of  tho 
tumultuous  debris  piles  formed  by  ice  streUms  than  any  other  deposits 
of  the  same  nature  now  forming  in  the  High  Sierra.  Like  the  majority 
of  the  glaciers  of  this  region,  the  one  at  the  head  of  Parker  creek  is  shel- 
tered by  overshadowing  walls,  and  flows  northward.  During  the  glacial 
epoch,  the  entire  extent  of  the  deep  valley  through  which  it  flows  was 
occupied  by  a  glacier  that  descended  upon  Mono  plain,  and  built  huge 
morainal  embankments  more  than  a  mile  in  length.  These  fine  examples 
of  the  peculiar  parallel  embankments  built  by  overloaded  glaciera  on 
emerging  from  mountain  gorges  are  second  in  interest,  however,  to 
similar  deposits  at  the  mouth  of  the  neighboring  gorge,  known  as 
Bloody  caflon,!  ^nd  illustrated  on  Plate  4. 

Characteristics  of  the  Glaciers  of  the  High  Sierra. 

That  the  ice  bodies  observed  in  the  High  Sierra,  although  small,  are  yet 
veritable  glaciers,  I  trust  will  appear  from  the  following  somewhat  detailed 
statement  of  observations  : 


1  The  instructive  records  left  by  Pleistocene  glaciers  in  the  nei{,'hborhood  of  Mono  lake 
are  described  and  illustrated  in  "Quaternary  History  of  Mono  Valley,"  in  the  8th  Annual 
Report  of  the  U.  S.  Geological  Survey,  1886-87,  pp.  261-394. 


^pp* 


42 


GLACIERS  OF  NORTH  AMERICA. 


N^vds.  —  The  distinction  between  n6v6  and  true  glacial  ice  is  plainly 
manifest  on  nearly  all  of  the  glaciers  of  the  High  Sierra.  This  is  apparent 
not  only  when  viewing  them  from  a  distance,  but  also  while  traversing 
their  surfaces.  In  the  case  of  the  Parker  Creek  glacier,  especially,  the 
change  from  the  granular  snow  of  the  neve  to  the  compact  ice  of  tlie  glacier 
proper,  can  be  discerned  within  the  space  of  a  very  few  feet.  The  neves, 
although  usually  dust-covered,  are  invariably  white  as  compared  with  the 
rest  of  the  glacier,  and  are  composed  of  granular  ice-snow.  Their  surfaces 
are  almost  entirely  free  from  stones  and  dirt,  and  are  rendered  very  rough 
and  uneven  by  crests  and  spires  of  compact  snow  or  neve  ice,  from  two  to 
five  feet  high,  that  result  fvom  the  unequal  melting  of  the  surface.  These 
"  ice  blades  "  have  been  described  by  Professor  Le  Conte,  who  refers  their 
origin  to  the  unequal  melting  of  wind-rippled  snow. 

At  their  lower  limits  the  n^v^s  pass  into  the  glaciers  proper,  which  in 
part  they  overlie,  and  acquire  a  ribboned  or  laminated  structure,  dirt 
bands,  etc.,  characteristic  of  true  glaciers. 

Crevasses.  —  Marginal  crevasses  were  observed  in  numerous  instances, 
but  they  occurred  in  quite  limited  numbei-s  in  any  individual  glacier.  In 
some  examples,  more  especially  in  the  neves,  they  are  convex  toward  the 
head  of  the  glacier,  while  others  far  down  in  the  same  series  are  straight, 
or  hrtve  changed  their  c  irvature  so  as  to  be  concave  up  stream.  The  cre- 
vasses are  largest  at  the  upper  margin  of  the  neves,  and  frequently  corre- 
spond to  the  bergschrund  of  Swiss  mountaineers.  They  vary  from  narrow 
cracks  up  to  chasms  six  or  eight  feet  wide,  and  frequently  cross  almost 
the  entire  breadth  of  the  neve,  thus  rendering  difficult  the  passage  to 
the  rocks  above.  The  depth  of  the  crevasses  could  seldom  be  deter- 
mined, as  the  irregularities  of  their  sides  limited  the  view,  but  some  were 
certainly  not  less  than  100  feet  deep.  The  crevasses  were  frei{uently 
partially  concealed*  by  arches  of  snow,  hung  within  with  vast  numbers  of 
icicles.  The  walls  beneath  these  treacherous  roofs  are  incrusted  with  large 
masses  of  well-formed  ice  crystals,  with  glittering  faces  half  an  inch  in 
diameter,  resembling  the  most  beautiful  transparent  spar.  The  light  in 
the^e  fairy-like  grottoes  is  of  the  most  exquisite  blue. 


Lamination,  or  ««  Ribboned  Structure."  —  This  structure  was  seen 
in  all  the  glaciera  closely  examined,  but  appeared  most  conspicuously 
near  the  lower  extremity  of  the  ice,  where  the  layers  are  approximately 
horizontal.     Hand  specimens  cut  from  the  ice  exhibited  sections  of  alter- 


is  plainly 
apparent 
ra  versing 
ially,  the 
le  glaciei 
he  neves, 
vk^ith  the 
?  surfaces 
3ry  rough 
m  two  to 
i.  These 
fers  their 

whicli  in 
ture,  dirt 


nstances, 

tcier.     In 

>ward  the 

straight, 

Tho  cre- 

tly  cf)rre- 

n  narrow 

is  almost 

;Ssage  to 

)e  deter- 

)me  were 

juently 

miners  of 

til  large 

inch  in 


light  in 


was  seen 
icuously 
ximately 
of  alter- 


■< 
> 


UJ       84 


3   .a» 

-J     6=1 

2  5 


o  a 

"  I 

"f.  o 

z  a 

°=  ^ 

-  I 


>-    u 


w 


w 


m 


n 
a 


A1 

I 

il 

e; 
tl 
la 

A! 
si 

Vi 

ir 

1)1 
tl 

tl: 


at 
la 
cl; 
It 
fa 
Cf 


su 
ar( 
ex 
su 
or 
on 
Fc 
Sv 
thi 
of 
ha 


GLACIERS   OF   THE   SIEKKA   NEVADA. 


43 


nating  narrow  bands  of  compact  blue  ice  and  porous  white  ice,  as  plainly 
as  could  be  desired. 


Dirt  Bands.  —  These  were  observed  on  nearly  all  of  the  glaciere,  and 
were  frequently  jnarked,  and  even  conspicuous,  features  of  their  surfaces. 
It  required  no  peculiar  condition  of  light  and  shade  to  make  them  discern- 
ihle  ;  on  the  contrary,  they  could  be  plainly  distinguished  at  a  distance  of 
two  or  three  miles.  Viewed  from  a  distance,  they  were  seen  to  sweep 
entirely  across  the  glacier  in  a  series  of  graceful  curves,  concave  toward 
the  neve.  Sometimes  this  symmetry  was  interrupted  by  irregular  undu- 
lations, or  even  by  contortions,  as  may  be  seen  in  the  illustnition  of  the 
Mount  Lyell  glacier.  On  Parker  Creek  glacier  the  dirt  bands  are  about 
six  inches  broad  over  a  considerable  area,  and  occur  at  quite  regular  inter- 
vals of  four  to  six  feet,  with  comparativiely  clear  ice  between.  In  this 
instance,  the  dirt  producing  the  bands  was  not  confined  to  the  surface, 
but  could  be  seen  to  discolor  the  ice  in  well-defined  strata,  dipping  into 
the  glacier  at  a  low  angle  with  the  surface.  On  all  of  the  glaciei-s 
examined,  the  dirt  bands  were  observed  only  below  the  lower  limit  of 
the  neve. 

In  the  study  of  the  glaciers  of  Switzerland  and  Norway,  particular 
attention  has  been  given  to  the  influence  of  ice  cascades  in  producing 
lamination  and  dirt  bands.  In  the  Sierra  Nevada  glaciei-s,  both  of  these 
characteristics  are  distinct  and  well  marked,  but  ice  cascades  are  absent. 
It  seems  evident,  therefore,  that  the  hypothesis  which  is  apparently  satis- 
factory in  Europe  does  not  agree  so  well  with  the  phenomena  observed  in 
California. 

In  viewing  many  of  the  Sierra  Nevada  glaciera  at  a  distance  of  a  few 
miles,  and  approximately  on  the  same  level,  it  is  appar'^nt  that  their 
surfaces  frequently  have  a  slope  of  from  15  to  more  than  30  degrees,  and 
are,  in  fact,  sections  of  the  ice  bodies  in  which  the  internal  structure  is 
exposed.  When  seen  in  this  manner  the  appearance  of  the  glaciers  is 
such  as  to  lead  one  to  suspect  that  the  dirt  bands  are  strata  in  the  ice, 
or  in  reality  "annual  rings"'  formed  by  yearly  accumulations  of  dirt 
on  the  n^ves.  A  similar  explanation  was  long  since  advanced  by 
Forbes  after  studying  the  dirt  bands  of  apparently  the  same  character  on 
Swiss  glaciers.  Prof.  H.  W.  Brewer  has  suggested  a  modification  in 
this  explanation  to  the  effect  that  a  year  of  exceptional  melting — one 
of  those  years  in  which  the  n6v6  is  reduced  to  the  minimum  —  would 
have  the  effect  of  combining  the  dirt  accumulated  during  several  years 


44 


GLACIERS  OF  NORTH  AMERICA. 


into  a  single  band,  which  would  represent  a  climatic  cycle  rather  than 
a  single  year.    This  explanation  agrees  best  with  the  facts  noted  above. 

Glacier  Tables.  —  Blocks  of  stone  perched  on  columns  of  ice,  and 
usually  designated  glacier  tables,  did  not  form  a  marked  feature  on  the 
ice  bodies  of  the  Sierra  Nevada  in  1883,  except  in  one  instance.  On 
Parker  Creek  glacier  they  were  numerous  and  in  all  stages  of  growth 
and  decadence.  Some  of  the  blocks  of  stone  were  poised  horizontally 
on  pedestals  of  ice ;  others  were  inclined  southward,  or  had  been  partially 
dislodged,  and  in  some  instances  they  had  fallen  and  were  lying  on  the 
southern  side  of  pinnacles  which  had  formerly  supported  them.  Sketches 
of  some  of  the  more  characteristic  examples  observed,  diawn  to  a  scale 
of  about  one  foot  to  the  inch,  are  here  shown. 


Fig.  3.  —  Glacier  Tableb,  Parkeb  Ckeek  Glacier,  California. 

The  largest  glacier  table  was  observed  near  the  cente/  of  the  Parker 
Creek  glacier,  a  few  hundred  feet  fro*^.^  its  terminus.  This  is  a  block  of  dense 
volcanic  rock  measuring  24  X  33  X  10  feet,  and  was  supported  by  a  column 
of  ice  eight  feet  high  on  its  northern  and  six  feet  high  on  its  southern  side, 
and  six  to  eight  feet  thick.  The  smallest  observed  blocks  that  are  able  to 
protect  the  ice  beneath  sufficiently  to  form  columns  as  the  general  surface 
melts  away  were  found  to  be  about  16x10x10  inches  ;  when  smaller 
"than  this  they  sink  into  the  surface  in  a  manner  that  is  well  known  to  all 
alpinists.  Small  pebbles  are  frequently  seen  at  the  bottom  of  little  ice 
wells  five  or  six  inches  deep,  but  good  examples  of  sand  cones  and  some  of 
the  other  minor  details  of  glacier  surfaces  were  not  observed. 


GLACIERS   OF   THE   SIERRA   NEVADA. 


45 


Ice  Pyramids.  —  As  the  forms  included  under  this  name  f urnisli  a 
detail  of  glacier  surfaces  not  described  before  the  glaciers  of  the  High 
Sierra  were  examined,  I  shall  transcribe  my  notes  concerning  them  at 
some  length. 

On  the  lower  portion  of  the  Mount  Lyell  glacier,  more  especially  than 
in  any  other  observed  instance,  the  surface  .bristles,  over  large  areas  in  the 
neve  region,  with  acute  pyramids  of  snow-ice  from  a  few  inches  to  fully 
tliree  feet  in  height,  with  bases  having  a  diameter  of  perhaps  one-half 
tlieir  height. 

At  the  base  of  each  pyramid  on  its  northern  side,  there  is  invariably  a 
stone,  sometimes  measuring  five  or  six  inches  in  diameter,  or  a  number  of 
loose  pebbles,  or  a  handful  of  dirt,  which  is  usually  depressed  somewhat 
below  the  general  surface  of  the  neve.     The  side  of  the  pyramid  rising 


Fio.  4.  — Ice  Pyramids,  Mount  Lyell  Glacier,  California. 


above  the  stone,  i.e.  the  northern  face,  is  usually  concave,  in  horizontal 
sections,  and  invariably  composed  of  clear,  compact  ice,  while  the  remainder 
of  the  structure  is  of  the  ordinary  porous  ice  forming  the  glacier  surface. 
Sometimes  the  nearly  horizonttil  lamination  of  the  glacier  ice  can  be  seen 
in  the  pyramids.  A  direct  relation  is  noticeable,  too,  between  the  size  and 
shape  of  the  stones  and  the  height  and  form  of  the  ice  pyramids  rising 
above  them. 

In  seeking  an  explanation  of  these  phenomena,  the  only  hypothesis  that 
seems  to  satisfy  the  observed  facts,  assumes  that  a  stone  or  jnass  of  dirt 
lying  on  the  surface  of  a  glacier  becomes  heated  and  melts  the  porous  ice 
beneath,  and  that  the  water  thus  formed  freezes  again  into  compact  ice, 
which  resists  the  sun's  heat  more  thoroughly  than  the  surrounding  porous 


46 


GLACIEUa   OF  NOltTH  AMEKICA. 


ice,  and  hence  is  left  as  the  general  surface  melts  away.  In  nearly  every 
instance,  the  stone  at  the  base  of  the  pyramid  had  been  carried  northward 
as  it  melted  its  way  downward,  thus  forming  the  steei),  northern  slope  of 
the  pyramid,  and  at  the  same  time  tending  to  prevent  the  formation  of  a 
prominence  on  the  northern  side  of  the  sunken  block.  The  pyramids 
alwa^'s  point  toward  the  noonday  sun,  hence  the  compact  ice  formed  on 
tiie  nortliern  side  of  a  pebble  is  more  exposed  than  the  ice  on  its  southern 
side,  and  is«  therefore,  more  rapitlly  melted. 

Moraines.  —  No  well-marked  medial  moraines  were  noticed  on  any  of 
the  Sierra  Nevada  glaciers.  The  reason  for  their  absence  is  because  the 
glaciei-s  are  simple  ice  streams,  without  tributaries.  Lateral  moraines 
resting  on  and  inclosed  in  the  ice  at  the  margins  of  the  glaciers  were  seen 
in  many  instances,  and  could  be  traced  without  difficulty  to  the  cliffs  fvom 
which  they  came.  Terminal  moraines,  however,  are  common,  and  occur 
at  the  lower  limit  of  every  glacier  observed,  and  owe  their  existence  to 
the  moderate  amount  of  morainal  material  scattered  over  the  surfaces 
or  contained  in  the  glaciers,  without  being  concentrated  into  medial 
moraines.  The  terminals  are  remarkable  for  their  size,  when  compared 
with  the  extent  of  the  parent  ice  streams,  indicating  that  the  process  now 
observed  has  been  going  on  essentially  as  at  present  for  a  long  term  of 
years.  The  terminal  moraine  now  forming  at  the  lower  extremity  of 
Mount  Dana  glacier  is  approximately  1000  feet  long  by  30  or  40  feet 
broad,  and  api)arently  100  feet  or  more  deep.  Below  this,  and  partially 
united  with  it,  is  a  second  ridge  of  debris  of  somewhat  greater  dirien- 
sions,  which  is  followed  by  other  similar  crescent-shaped  piles  lower 
down  the  gorge.  The  corresponding  moraines  at  the  extremity  of 
Mount  Lyell  glacier  are  considerably  larger,  as  are  also  the  still  more 
typical  terminals  at  the  foot  of  the  Parker  Creek  glacier.  In  some 
instances  these  moraines  were  coated  with  loose  rubbish  and  dirt  that 
would  be  swept  away  by  a  single  storm,  indicating  that  they  had  received 
their  last  addition  within  a  very  few  months. 

The  bottom  of  the  Dana  glacier  was  seen  to  be  heavily  charged  with 
stones,  pebbles,  and  sand,  and  to  rest  on  a  bed  of  boulders  of  a  consider- 
able thickness.  This  subglacial  deposit  may  with  propriety  be  termed  a 
ground  mor9,ine. 


Glaciated  Surfaces  and    Scratched  Stones.  —  The  rock  surfaces  in 
the  immediate  neighborhood  of  the  Sierra  Nevada  glaciers  are  frequently 


OLACIEHS    OF   THK    SIEKHA    NEVADA. 


47 


polished  and  covered  with  grooves  and  scratches,  bnt  it  is  usually  impos- 
sible to  determine  whether  this  is  the  work  of  existing  ice  streams,  when 
somewhat  more  extended  than  at  present,  or  whether  it  is  a  part  of  the 
vast  glaciation  imposed  upon  all  the  High  Sierra  during  the  glacial  ei»()ch. 
ill  some  instances,  however,  there  does  not  seem  room  for  doubting  that 
the  markings  were  made  during  the  past  few  years. 

At  the  inmiediate  foot  of  Mount  Dana  glacier,  we  found  a  numl)er  of. 
stones  that  were  battered  and  worn  and  exhibited  planed  and  scratched 
surfaces,  in  many  respects  similar  to  the  glaciated  stones  found  in  the 
ancient  moraines  of  New  England.  These  occurred  but  a  few  feet  from 
the  ice  foot,  and  their  bruises  and  scratches  are,  without  question,  the 
work  of  the  present  glacier. 

Glacier  Movements.  —  That  the  small  ice  bodies  of  the  Sierra  Nevada 
have  a  true  glacial  motion  is  apparent  from  the  nature  of  the  crevasses 
and  the  curved  coui-ses  of  the  dirt  bands  that  cross  them.  Measurements 
of  the  movements  of  these  glaciers  have  been  made  in  only  a  few  instances. 
The  rate  of  the  flow  of  the  glacier  on  Mount  McClure  was  determined  by 
John  Muir,  who  found  that  its  maximum  movement  near  the  center  was 
about  47  inches  in  46  days  (from  August  21  to  October  0,  1872).  A 
more  extended  notice  of  these  interesting  observations  is  given  in  record- 
ing "previous  observations"  a  few  pages  in  advance. 

Glacier  Mud.  —  The  Tuolumne  river  has  its  source  at  the  foot  of 
Lyell  glacier.  At  its  birth  it  is  a  rivulet,  turbid  with  silt  ground  fine  by 
the  moving  ice  from  beneath  which  it  issues.  At  the  foot  of  the  Dana 
g^laoier  there  is  a  small  lake  confined  in  a  rock  basin,  which  has  a  peculiar 
greenish-yellow  color  dlie  to  silt  held  in  suspension.  The  water  escapes 
from  this  lake  through  a  moraine  piled  on  the  rim  of  the  basin,  and  is 
gathered  again  into  other  depressions  farther  down  the  caflon.  The 
watei"S  are  thus  filtered  of  matter  in  suspension,  and  the  lower  lakes  are 
clear  and  blue,  like  hundreds  of  other  lakelets  and  tarns  scattered  over 
the  surrounding  glaciated  area.  The  sediment  contributed  to  these  glacial 
waters  is  so  extremely  fine  that  it  requires  days  and  perhaps  weeks  to  settle. 


Ice  Tongues. —  In  the  steep  walls  of  the  amphitheatres  overlooking 
the  n6vds  of  the  glaciers  here  considered,  there  are  frequently  deep,  nar- 
row clefts  leading  toward  the  higher  peaks.  In  many  instances  they  are 
partially  filled  with  ice,  which  shoots  up  above  the  n^v^s  in  tapering 


48 


GLACIERS   OF   NORTH   AMERICa.. 


tongues  some  hundreds  of  feet  in  height  and  at  so  steep  an  angle  that  it 
is  impossible  to  ascend  or  descend  them  without  cutting  steps.  These 
ice  tongues  are  interesting  features  of  the  Sierra  glaciers  and  are  also 
known  to  occur  at  the  heads  of  similar  ice  streams  in  Wyoming. 
One  of  them,  in  the  shadow  of  a  precipice,  is  shown  on  Fig.  A,  Plate 
2.  Whether  they  have  glacial  motion  or  not,  has  never  been  deter- 
mined. They  appear  to  have  originated  from  the  freezing  of  watei-s 
flowing  from  adjacent  areas,  and  not  to  have  been  formed  entirely  by 
the  consolidation  of  n6\6  snows,  after  the  manner  of  true  glacier  ice. 

Red  Snow.  —  While  Mr.  Gilbert  and  myself  were  examining  the 
n^ve  portion  of  the  Mount  Lyell  glacier,  we  noticed  that  our  foot- 
prints in  the  snow  had  a  bright  pinkish  tint,  '.^hile  the  undisturbed 
surface  appeared  white  or  perhaps  grayish  white.  At  the  lower  border 
of  the  nev6  the  color  became  more  distinct  and  could  be  plainly  seen 
in  the  untrodden  snow,  and  in  som?  instances  the  borders  of  rills 
were  outlined  by  delicate  pencilings  of  crimson.  In  all  cases  the 
"  red  snow "  was  superficial,  or  at  most  only  covered  by  a  thin  layer 
of  fresh  snow.  Some  of  the  coloring  matter  collected  was  examined 
under  the  microscope  a  number  of  months  later  and  found  to  consist 
of  red  globules  from  150  to  200  millimeters  in  diameter,  which  were 
determined  to  be  the  minute  algae  known  as  Protococcus. 


Surface  Melting:* — Our  examination  of  Mount  Lyell  glacier  began 
one  August  morning  before  sunrise,  when  the  vast  amphitheatre  in  which 
the  ice  is  cradled  was  hushed  in  the  profound  stillness  peculiar  to 
mountain  tops.  As  the  sun  rose  above  the  granite  spires  to  the 
eastward  and  flushed  the  snow  fields  with  a  ruddy  light,  little  rills  started 
here  and  there  on  the  glacier,  gradually  gathering  strength  as  the 
sun's  warmth  increased,  and  by  noon  brooks  of  considerable  size  were 
rushing  down  channels  of  ice,  but  sooner  or  later  they  plunged  into 
crevasses  and  were  lost  to  sight.  At  midday  the  murmur  of  water 
was  heard  everywhere  over  the  glacier.  As  the  chill  of  evening  came 
on  the  music  of  the  streams  gradually  ceased,  and  by  sunset  a  death- 
like silence  reigned  over  the  frozen  region. 

That  this  noonday  melting  has  more  than  counterbalanced  the 
annual  additions  received  during  the  years  previous  to  our  visit,  seems 
evident  from  accounts  of  the  former  extent  of  the  snow  fields  of  the  High 
Sierra.    The  observations  bearing  upon  this  point  are  given  below.    From 


GLACIERS   OF  THE   SIERRA   NEVADA. 


49 


all  that  has  been  learn«d  concerning  the  fluctuations  of  the  glaciers  of 
Ciilifornia,  it  appears  that  like  those  of  Switzerland,  they  are  subject  to 
periodic  changes,  due  principally  to  climatic  oscillations.  Since  their  dis- 
covery they  have  apparently  not  been  increasing. 

Pioneer  Explorations  in  the  High  Sierra. 

Although  giving  precedence  to  my  own  observations  in  describing  the 
gla(aei's  of  the  High  Sierra,  it  is  not  my  intention  to  ignore  the  reports  of 
those  who  preceded  me  in  the  same  field. 


.rolin  Muir. — An  anonymous  article  on  the  "  Living  Glaciers  of  Cali- 
fornia," which  appeared  in  the  Overland  Monthly  for  Decemlxjr,  1872, 
and  now  known  to  have  been  from  the  pen  of  John  Muir,  is,  so  far  as  I 
tan  learn,  the  first  announcement  of  the  existence  of  glaciers  on  the  Sierra 
Nevada.  Mr.  Muir  states  that  in  October,  1871,  he  was  among  the 
nionntains  of  the  Merced  group  and  found  a  living  glacier,  with  very- 
recent  moraines  at  its  foot,  from  beneath  which  issued  a  stream  of  turbid 
w liter.  Furthv'r  observatio.i?  revealed  dirt  bands,  crevasses,  and  lateral 
moraines,  thus  leaving  no  doubt  that  the  "  snow  bank,"  as  it  had  pre- 
viously been  considered,  was  an  actual  glacier.  Other  similar  ice  bodies 
were  examined  by  Mr.  Muir,  on  Mount  Lyell  and  Mount  McClure  ;  and 
from  the-  top  of  the  former  peak  he  saw  a  dozen  snow  and  ice  filled 
cirques  on  neighboring  mountains. 

In  August,  1872,  Mr.  Muir  placed  five  stakes  in  the  glacier  on  Mount 
McClure,  for  the  purpose  of  demonstrating  whether  or  not  it  ha<l  true 
glacial  motion.  Four  of  these  stakes  were  ranged  in  line  from  the  east 
side  to  a  point  near  the  middle  of  the  glacier,  the  fii-st  being  25  yards 
fiom  the  east  bank  ;  the  second,  94,  the  third,  152,  and  the  fourth,  225 
yards  respectively.  On  observing  the  stakes  on  October  6,  forty-six  days 
after  being  placed  in  position,  it  was  found  that  No.  1  had  been  carried 
down  the  glacier  11  inches  ;  No.  2,  18  inches  ;  No.  3,  34  inches  ;  No.  4, 
47  inches.  Stake  No.  4  was  near  the  middle  of  the  glacier,  and  its  dis- 
placement was  thought  to  iniicate  the  maximum  motion  of  the  ice. 
Stake  No.  5  was  placed  about  midway  between  the  head  of  the  glacier 
and  No.  4.  Its  motion  was  40  inches  in  forty-six  days.  These  measure- 
ments, though  not  as  detailed  and  perhaps  not  as  accurate  as  could  be 
desired,  are  yet  sufficient  to  demonstrate,  as  claimed  by  Mr.  Muir,  that 
the  ice  in  this  instance  had  true  glacial  motion.     In  this  example,  as  in 


w 


60 


GLACIEU8    OF   NORTH    AMERICA. 


moHt  noiniiil  glaciers,  the  greatest  movement  wuh  near  the  middle  of  the 
iee  Htreani. 

The  Mount  McClure  j^lacier,  when  visited  by  Mr.  Muir,  was  approxi- 
mately half  a  mile  long  and  of  about  the  same  breadth  in  the  widest  part, 
and  was  olwerved  to  Ix)  traversed  in  the  southeast  corner  by  eroviusses 
s(!veral  yanls  long,  but  oidy  about  a  foot  wide.  The  Mount  Lyell 
glacier,  in  1872,  is  stated  to  have  l)een  about  a  mile  in  length  by  a  mile 
in  breadth. 

Mr.  Muir  also  describes  narrow,  high-grade  caSlons,  called  "  devil's 
slides,"  "  devil's  lanes,"  etc.,  which  occur  about  the  higher  peaks  and  are 
frequently  occupied  by  ice.  In  one  of  these  gorges  the  ice  was  found  to 
have  a  motion  of  a  fraction  of  an  inch  a  day.  These  small  ice  bodies 
are  what  I  have  called  "  ice  tongues  "  in  describing  my  own  observations. 
It  is  to  be  lioped  that  further  information  concerning  their  origin  and 
behavior  may  be  obtaine'd,  since,  so  far  as  is  known,  they  do  not  appear  in 
mor«!  heavily  glaciated  regions. 

In  an  article  entitled,  "In  the  Heart  of  the  California  Alps,"^  Mr. 
Muir  gives  some  account  of  the  glaciei-s  about  Mount  Kitter,  combined 
with  enthusiastic  descriptions  of  the  magnificent  scenery  of  the  Sierra. 
In  another  article  from  the  same  pen  on  "  Living  Glaciers  of  California,"  '^ 
several  illustrations  of  glacial  scenery  are  introduced,  together  with 
popular  descriptions  of  numerous  ndves  and  ice  fields. 

JoHopli  Lie  Conte. — Professor  Joseph  Le  Conte  visited  the  High 
Sierra  during  the  summera  of  1872  and  1873,  and  in  company  with  Mr. 
Muir  examined  the  sun^  it  of  Mount  Lyell.^  In  describing-  the  records 
of  the  ancient  glaciei-s  that  once  filled  the  Tuolumne  valley,  Le  Conte 
says,  that  what  interested  him  far  more  than  anything  else  seen  during 
his  journey  "  was  that  on  the  main  branch  of  the  Tuolumne  river,  far  up 
among  the  cliffs  and  peaks  of  Mount  Lyell,  still  exists  a  living  glacier,  in 
a  feeble  state  of  activity,  it  is  true,  but  certainly  living."     Professor  Le 


1  Rcribner's  Monthly,  vol.  20,  1880,  p.  346.  \ 

2  Harper's  Magazine,  vol.  61,  1875,  p.  769.  A  brief  account  of  the  discovery  of 
glaciers  in  the  Sierra  Nevada,  and  of  some  of  their  more  prominent  features,  may  be  found 
in  a  charming  book  by  John  Muir,  entitled  "The  Mountains  of  California,"  London,  18114. 

*  A  portion  of  the  observations  made  during  these  journeys  was  published  in  a  paper, 
"  On  some  of  the  Ancient  Glaciers  of  the  Sierra,"  Proceedings  of  the  California  Academy  of 
Sciences,  vol.  4,  1872,  p.  169;  and  also  in  a  more  extended  form,  in  the  American  Journal 
of  Science,  Third  Series,  vol.  6,  1873,  p.  325.  See  also  Le  Conte's  "Elements  of  Geology," 
revised  edition,  1882,  p.  «02. 


GLACIEK8   OF   THK   HIKUKA    NEVADA. 


61 


('onto  accepts  Mr.  Mitii-'s  mensurement,  and  concludes  that  "the  ijlacier 
iiiittlon  titill  i'j-iiitn."' 

Mount  Lyell  j^hicier  appears  to  have  Imjcu  more  completely  hidden  by 
snow  when  examined  l)y  l^e  Contc  in  1H72  than  when  seen  by  the  present 
writer  ten  yearo  later.  Le  Conte's  account,  from  the  American  Journal 
of  Science,  referred  to  alK)ve,  is  as  follows  : 

"  Here,  then,  on  Mount  Lyell,  we  have  now  existing,  not  a  true  i/lacier, 
perhaps,  certainly  not  a  typlml  (/lacier  (since  there  is  no  true  glacitn-  ice 
visii)lo,  but  only  snow  and  n6v^,  and  certainly  no  protmxion  of  an  ice 
tontfue  beyond  the  snow  field)^  yet,  nevertheless,  in  some  itense  a  ylacier, 
since  there  is  true  differential  motion  and  a  well-marked  terminal 
moraine.  It  is,  in  fact,  a  glacier  in  feeble  old  age,  a  feeble  remnant  of  the 
Tuohnnne  glaciei\  a  glacier  once  of  great  proportions  and  j)laying  ';n 
important  part  in  mountain  sculpture,  but  now  in  its  second  childhood." 

Le  Conte  fouuvl  the  surface  of  the  snow  on  the  n6v6  of  the  Lyell  gla- 
cier "traversed  in  a  diiection  at  right  angles  to  the  slo})e  by  aharj)  blades 
of  half-compacted  ice  about  two  feet  apart  and  two,  three,  four,  or  even 
live  feet  in  height ;  .  .  .  the  crests  of  the  i^lades  were  not  continuous, 
hut  irregular,  both  in  outline  and  trend,  very  much  in  this  respect  like 
ripple  marks  or  like  waves."  ^  Ihe  explanation  offered  —  suggested  by 
Mr.  T.  C.  Gardner — is  that  the  blades  are  due  to  the  action  of  the  sun  on 
wind-ripples  formed  on  the  surface  of  the  nev6. 


m 


Geological  Survey  of  California. — In  the  publication  of  the  Geological 
Survey  of  California,  no  mention  is  made  of  existing  glaciers  in  the  Sierra 
Nevada.  The  frontispiece  of  Volume  1  (Geology),  showing  Mount  Lyell 
as  seen  from  Tuoli  nine  valley,  and  also  a  sketch  of  the  summit  of  the 
peak,  forming  Figure  73,  indicate  that  the  mountains  were  then  far  more 
heavily  mantled  with  snow  than  in  1882  and  1883.  Professor  J.  D. 
Whitney,  formerly  State  Geologist  of  California,  in  his  work  on  "  Climatic 
changes  of  later  geological  time,"'^  says,  "It  may  be  stated  that  there  are 
no  glaciers  in  the  Sierra  Nevada  proper  and  none  in  the  Great  Basin  or 
Kocky  Mountain  ranges,  at  least  south  of  the  parallel  of  42  °.  With  the 
exception  of  some  recent  discoveries  said  to  have  been  made  in  1878,  in 
the  Wind  River  range  (about  latitude  43'^)  by  the  U.  S.  Geological  Sur- 
veying party,  of  which  no  definite  account  seems  as  yet  to  have  been  pub- 

1  American  Journal  of  Science,  Third  Series,  vol.  5,  1873,  p.  3.32. 
*  Memoirs  of  the  Museum  of  CompF.rative  Zoology  of  Harvard  College,  vol.  7, 1882, 
no.  2,  p.  25. 


52 


GLACIER8   OF   NORTH   AMERICA. 


ml 
mm 


lished,  it  may  be  stated  that  there  are  no  proper  glaciers  anywhere  within 
the  limits  of  the  United  States  (Alaska  not  included)  except  around  the 
great  isolated  volcanic  cones  of  the  Pacific  coast.  There  are  certainly 
none  in  the  higher  portions  of  the  Sierra  Nevada  or  the  Rocky  mountains, 
these  most  elevated  regions  having  been  sufficiently  explored  lo  ascertain 
that  fact."  It  will  be  noticed  that  this  passage  was  published  in  1882,  or 
ten  yefvrs  later  than  Muir's  and  Le  Conte's  observations  citeti  above.  On 
pag'd  30  of  Profess;  T-  Whitney's  work,  the  notes  of  Messrs.  King  and 
Gardner  made  in  1868,  while  exploring  the  eastern  slope  of  Mount  Hitter, 
are  transcribed  as  follows  :  "  In  a  deep  cul-de-sac  which  opens  southward 
on  the  east  slope  [of  Mount  Ritter]  lies  a  bed  of  ice  200  yards  wide 
and  about  half  a  mile  long.  It  has  moved  down  from  the  upper  end 
of  the  gorge  for  30  or  40  feet  this  year,  leaving  a  deep  gulf  between  the 
vertical  stone  wall  and  the  ice."  In  connection  with  these  observations 
Professor  Whitney  remarks  that  "  it  is  doubtful  whether  these  residual 
masses  of  ice  can  with  propriety  be  called  glaciers." 

iOlarence  Kiii^r.  —  Mr.  King  also  rejected  Mr.  Muir's  observations,  as 
is  shown  by  several  emphatic  passages  in  his  Report  of  the  Exploration  of 
the  40tli  Parallel,^  but  adds  no  new  information  on  the  subject. 

Conditions  Favoringr  Observation.  —  From  these  quotations  it  will 
be  seen  that  the  question  of  the  existence  of  glaciers  in  the  Sierra  Nevada 
nas  been  decided  diiferently  by  different  observers,  who  perhaps  saw  the 
mountains  under  diverse  conditions  as  regards  their  snowy  covering.  In 
winter  the  glaciers  are  so  deeply  snow-covered  that  no  one  would  suspect 
their  existence  ;  it  is  only  late  in  summer,  when  the  snows  have  decreased 
to  a  minimum,  that  they  are  to  be  seen  to  the  greatest  advantage.  That 
Mr.  Muir  was  correct  in  classing  many  of  the  snow  masses  among  true 
glaciers,  has  been  sustained  by  recent  studies,  but  the  observations  on 
which  his  decision  was  based,  were  not  sufficiently  extended  to  convince 
several  geologists  who  visited  the  mountains  when  more  completely  snow- 
covered  thar.  at  the  time  the  measurements  referred  to  above  were  made. 

Ancient  Glaciers. 

It  is  necessary  in  the  present  volume  to  restrict  attention  to  living 
glaciers,  but  in  passing,  I  may  mention  that  all  of  the  higher  portions  of 
the  Siei.a  Nevada,  evcepting  the  very  highest  peaks  and  crests,  were 

1  Vol.  1,  pp.  447,  448. 


'  '  ■  " ' 

1 

V 

itiiiili 

iiji 

HP": 

H 

"" ' '  ' 

L 

I     lltllhlli                          "Vi 

f-  ■''  W\  '■.*; 

^l                  -.•;■:•■;-*> 

.•^    '■  ■■■"■"■■■    jt'  ■             1 

< 

!|  '1    I       1  M{  1 

'  't| 

iilll      il 

■>  .^^  V 

%ff        i 

< 

z 

^ 

[ill  11         1 

81 

1     1 

«'  -  V^  ■       *  '   1  .  A 

f    ^'             ' 

*  '  •'' i^^ 

cc 

I 

t    f^   '5v^    k 

"       n                   ,,         V' 

'.■■"'^^t 

O 

1 

,  V.ilV  '>>J  1  V-. 

'               k                        V 

,■' '  ''■¥%■' 

Li. 

1 

;'/n  «^'  ";• 

\         •'                         '                'k 

■    '■  ■      -^KLi.' 

_l 

■yjl'         1        jl      ^ 

V 

'  i  i^^-^SI    '  ' 

■< 

1           1 

' ;  :  ■  '^^ 

o    > 

1     1      1 

p  £■''   ""■        '  *'' 

•   .1 

''''.■         •   .' 

■ 'I  v^^/:m 

>-    ■/ 

• 

r  ii'  1    1  11 

> 

|/'.v.^^'> 

til: 

>    a, 
z     3 

• 

1  1    1 

1/ 

lll^ji^'- 

■  ^;**'\'  'M^'l?^ 

'■■fe:A/v  mini 

in  |i 

HF|:i\.  i'l^r  i-^ 

iRiL    ■'%'■■■■  ^^•''' 

J 

III    1 . 

111'-       "-,^%^^/f '>t'" 

b^^OAlBl 

^Hli 

d     si 

■'ilni'i'  :,i   1 

>    ^ 

V 

W4 

|C:,.&  '   . 

Q     a 

1  ii- 

|:i'i 

11^^     j^       Ai-'"^.': 

mSBSSHp!^'  f 

-J    5 

1 

fif^P        Jf''^>v  ■ 

,      IP.     4    Vf 

WBl^mMW^m 

00     <* 

'  i'l 

i*'-'| 

Mm       'jy^;';;' 

'"                 '    1    1 

jgro^sMii^li 

u.    3 

B-M 

Hiif  <i( 4!'^*'i4^ i           jr  'i 

■-,■■■        ■     ■'*■■■  \ 

v^BV^MflMMlulllufl 

O    .9 

f."  '  '  ^':'« 

I  1 

II  i 

■■'-'?V':'<:>-      V      ''' 

tf;':..S«'^>:> 

I    ^ 

• 

1 

|.  <^  Mjs!^^KL^' i^H^^^H 

•■■%\*-v    \- 

^^il^HBfi&VJiBrAJijI^H 

t-      5 

;    , 

:  i 

m     ^^l^^Bf^-  "^B^^^B 

..    --A^^-'    >^-.> 

fr^H^Hrj||^jK'''^H 

3    2 

.-. 

i      ! 
1  1 

1 

1 1 
1 1 

1 1 1|^  '^m^r:'  |Hh 
Ii;.;.  ,      iKgHa^P^I 

V 

1    ^4iMJw^Hft^l«S^^^H9l 

1     iiJBTr^BrTff^  IMMraBlll 

H7'nV''^BlEti^^^afn& 

!^  1 

CO     J 

1 

! 

Win  & ' '  'iiw        ^!yr       ■''■' ' 

m'L'li"'--^" 

r,:  '''V  -'''^K- 

(-    a 

If          1 

:  1 

li'ii 

il 
iilll 

Wrl     \ft. 

c^p  • . 

z      " 

^  i 

■H 

'Ml      |:iil 

L  '.;■>,,.         V:  '■'•'' 

^^Mft^A 

i^M   * 

-  1 

< 

II        ' 
■             11' 

ft.  1',,  ^'^  ,          -; ,  ,/ ' 

HoBiijayHBH^n 

m    a* 

t. 

1]  III  i  y> ! 

1 

:ii,::{n^^^^^V             nBl^ffi 

l^H  ''|%.^WiHBI 

2     5 

1 

u 

■   r  '    •'Wt^v 

Pi'^wilw 

^     -<! 

S 

il  1   Ur          :  -'•:^F«L\,l 

ro 

_J 

< 

1 

ii 

!i  1 

i\ 

Ml    1 

1 

1  nPWPWHILv    iiy 

•< 
z 

QC 

o 

2 

^ 

1    ''> 

Il       1 

1  ^^^Hk^%  mi 

PI 

a 

w 

1 

iiii 

il 

111  ]l 

il 

„,: 

--■---■ 

• 

'  'i     ■- 

< 

IfTTl 


ff 


Ina 
fro: 
tlia 
cip 
we] 
bod 
the 
niel 

noil 

con 

fror 

Tin 

the 

The 

the 

300 

but 

SOU! 

San 

tied 

to  t] 

defi] 

they 

nior; 

caiio 

feati 

Pari 

Parli 

moi'ii 

first 

built 

retre 

secoi 

a  pai 

adva 

mora 

OCCU] 

Mou( 


GLACIERS   OF   THE   SIERRA   NEVADA. 


58 


loaded  with  snow  during  the  glacial  period,  so  as  to  form  a  vast  ndv^ 
from  which  large  ice  streams  flowed  in  various  directions.  Tlie  glaciers 
that  went  Avestward  were  far  larger  tiian  those  that  descended  the  pre- 
cipitous eastern  escarpments.  In  several  instances  the  ancient  glaciers 
were  majestic  rivera  of  ice  30  or  40  miles  long.  The  present  ice 
l)odies  are  the  shrunken  remnants  of  these  ancient  ancestoi-s,  or  else  mark 
the  beginning  of  a  new  cycle,  the  former  glaciers  having  been  completely 
melted. 

In  the  High  Sierra  to  the  westward  of  Mono  lake,  the  more  pro- 
nounced topographical  features  resulting  from  the  ancient  glaciation  are 
conspicuously  displayed.  The  broad-bottomed  valley  leading  northward 
from  Mount  Lyell  was  formerly  occupied  by  the  great  Tuolumne  glaciar. 
This  received  an  important  tributary  from  the  region  about  Mount  Dana, 
the  path  of  which  is  deeply  engraved  in  the  topography  of  the  country. 
The  glacier  formed  by  the  union  of  these  two  ice  streams  flowed  down 
the  Tuolumne  canon  for  30  or  40  miles,  with  a  depth  of  between  2000  and 
3000  feet ;  and  it  is  believed  to  have  occupied  the  Hetch-Hetchy  valley, 
but  its  full  extent  is  not  known.  Other  magnificent  glaciers  having  their 
sources  about  Mount  Lyell  and  Mount  Ritter  descended  the  Merced  and 
San  Joaquin  valleys,  which,  like  the  Tuolumne  caflon,  were  greatly  modi- 
fied by  ice  erosion.  To  the  eastward  of  the  divide  between  the  drainage 
to  the  Pacific  and  the  Great  basin,  the  paths  of  the  ancient  glaciers  are 
definitely  recorded  by  the  smoothed  and  rounded  contours  of  the  valley, 
they  occupied.  Their  channels  are  frequently  fringed  with  lateral 
moraines,  which  in  some  instances  were  carried  beyond  the  mouths  of  the 
canons  and  prolonged  upon  the  plain  as  parallel  f  nbankments.  This 
feature  is  especially  illustrated  by  the  moraines  at  the  mouths  cf  Bloody, 
Parker,  and  Rush  Creek  caRons  in  Mono  valley.  At  Bloody  caflon  and 
Parker  creek  two  .  parate  extensions  of  the  glaciers  are  recorded  by  the 
moruinal  embankments.  The  glacier  that  flowed  down  Bloody  caflon  at 
first  a(  anced  upon  the  plain  with  a  slight  deflection  to  the  right  and 
built  o  a  pair  of  huge  morainal  embankments;  subsequently  the  ice 
retreatei  it  least  as  far  as  the  mouth  of  the  caflon,  and  then  advanced  a 
second  time  with  a  deflection  to  the  left,  i.e.  northward,  and  formed 
a  pair  of  parallel  embankments,  still  larger  than  the  first.  Tv/o  similar 
advances  of  the  Parker  Creek  glacier  are  recorded  by  the  very  perfect 
morainal  embankments  still  remaining.  The  ice  stream  which  formerly 
occupied  the  valley  of  Rush  creek  was  by  far  the  largest  that  entered  the 
Mono  basin,  and  left  man^  features  of  interest.     As  shown  by  smoothed 


54 


GLACIERS   OF   NORTH    AMERICA. 


rock  surfaces  and  by  well-preserved  moraines,  this  glacier  was  over  1500 
feet  thick  where  it  left  the  caflon:  before  reaching  the  plain  it  was 
divided  by  a  high  rocky  spur  into  two  branches.  The  more  southern 
branch  deposited  terminal  moraines  in  such  a  way  as  *to  obstruct  the 
outlet  of  the  valley  and  cause  a  reversal  of  the  stream  when  the  glacier 
melted. 

The  evidence  left  by  ancient  glaciers  in  the  Sierra  Nevada  is  a  part  of 
the  records  of  a  Great  Ice  age  found  throughout  the  northern  half  of 
North  America  and  in  many  other  parts  of  the  world,  and  falls  properly 
in  a  history  of  Pleistocene  times.  The  records  of  this  history  can  be 
properly  understood  only  by  comparing  them  with  similar  inscriptions 
now  being  made.  The  study  of  existing  glaciers  is  thus  a  preparation 
for  the  still  greater  task  of  deciphering  the  records  of  periods  of  ancient 
glaciation. 


CHAPTER  IV. 

QLACIBr.S  OF   NORTHERN   CALIFORNIA  AND  THE   CASCADE 

MOUNTAINS. 

The  Sierra  Nevada  is  considered  as  terminating  at  the  northward 
near  the  northern  boundary  of  California ;  but  whether  this  is  in  reality  the 
limit  of  the  disturbance  that  elevated  the  range  remains  to  be  positively 
determined.  The  same  great  series  of  mountains  so  pronounced  in 
northern  California  is  continued  northward  as  a  prominent  topographical 
feature,  through  Oregon  and  Washington  far  into  British  America. 
North  of  California  the  chain  had  received  the  name  of  the  Cascade  moun- 
tains, and,  unlike  the  Sierra  Nevada,  is  largely  composed  of  lava  sheets. 
The  volcanic  overflows  commence  southward  from  what  is  generally  con- 
sidered as  the  southern  extremity  of  the  Cascade  range,  and  form  the 
grandest  peaks  in  northern  California.  When  the  region  is  better  known, 
perhaps  the  more  southerly  peaks  will  be  classed  in  the  same  group  as 
Tacoraa,  Jeffel'son,  Hood,  etc.  These  grand  cones,  the  glory  of  the  North- 
west coast,  have  been  but  imperfectly  explored,  yet  enough  is  known  to 
assure  us  that  many  of  them  are  glacier-crowned. 


Mount  Shasta. 

(A  map  of  the  glaciers  on  Mount  Shasta  is  given  on  Plate  5.) 

Observations  by  Clarence  King. — The  earliest  account  of  the  glaciers 
of  Mount  Shasta  is  given  by  Clarence  King,  who  in  company  with  several 
members  of  the  U.  S.  Geological  Exploration  of  the  40th  Parallel,  as- 
cended the  peak  in  September,  1870.  From  a  report^  of  this  pioneer 
climb,  I  have  transcribed  the  portion  relating  to  glaciers  : 

"On  September  the  11th,  we  climbed  to  the  top  of  the  lesser  Sliadca 
[named  Shastina  crater  on  Plate  5],  a  conical  secondary  crater  jutting  out 
from  the  main  mass  of  the  mountain  on   its  northwest  side.  .  .  .  We 


1  American  Journal  of  Science,  Third  Series,  vol.  1,  1871,  p.   157.     A  more  popular 
account  was  published  in  "  Mcantaineerin''  in  the  Sierra  Nevada,"  by  the  same  author. 


II::; 


66 


GLACIERS   OF   NOKTH   AMEHICA. 


m ! 


-i  -5#--*-',"  ■-   .- 


reached  the  rim  of  the  cone,  and  looked  down  into  a  deep  gorge  lying  be- 
tween the  secondary  crater  and  the  main  mass  of  Shasta,  and  saw  directly 
beijeath  us  a  fine  glacier  [since  named  Whitney  glacier  ;  see  Plate  5  an<l 
Figure  A,  Plate  6],  which  started  almost  at  the  very  crest  of  the  main 
mountain,  flowing  towards  us,  and  curving  around  the  circular  base  of 
our  cone.  Its  entire  lengLh  in  view  was  not  less  than  three  miles,  its 
width  opposite  our  station  about  4000  feet,^  the  surface  here  and  there 
terribly  broken  in  'cascades,'  and  presenting  all  the  characteristic  fea- 
tures of  similar  glaciers  elsewhere.  The  region  of  the  terminal  moraine 
was  more  extended  than  is  usual  in  the  Alps.  The  piles  of  rubbish  super- 
imposed upon  the  end  of  the  ice  indicated  a  much  greater  thickness  of 
the  glacier  in  former  days.  After  finishing  our  observations  upon  the 
side  crater  and  spending  a  night  upon  the  sharp  edge  of  its  rim,  oa  the 
following  morning  we  climbed  over  the  divide  to  the  main  cone,  and  up 
to  the  extreme  summit  of  Shasta,  a  point  14,440  feet  above  the  sea  level. 
From  the  crest  I  walked  out  to  the  northern  edge  of  a  prominent  spur 
and  looked  down  upon  the  system  of  three  considerable  glaciers,  the 
largest  about  four  and  one-half  miles  in  length  and  two  or  three  miles 
wide.  On  the  next  day  we  descended  on  the  south  side  of  the  cone, 
folL  ving  the  ordinary  track  by  which  earlier  parties  have  made  the  climb. 
From  the  moment  we  left  the  summit  we  encountered  less  and  less  snow, 
and  at  no  part  of  the  journey  were  we  able  to  see  a  glacier.  An  east  and 
west  line  divided  the  mountain  into  glacier-bearing  and  non-glacier- 
bearing  halves.  The  ascent  was  formerly  made  upon  the  north  side, 
where,  as  stated,  there  are  no  glaciera,  and  this  is  why  able  scientific 
observers,  like  Professor  Whitney  and  his  party,  should  have  scaled  the 
mountain  without  discovering  their  existence. 

"Before  and  after  the  ascent  of  Mount  Shasta,  a  week  was  given  for  an 
examination  of  the  southern  half  of  the  volcano.  Since  the  earliest  settle- 
ment of  Strawberry  and  Shasta  valleys,  there  has  never  been  such  a  com- 
plete denudation.  From  June  to  November  the  snow  masses  were  less 
than  they  have  ever  been  seen  before.  This  favored  greatly  our  geologi- 
cal observations,  and  gave  us  an  excellent  opportunity  to  study  the  relics 
of  the  former  great  neve.  We  explored  one  after  another  all  the  caiions, 
whi(5h,  approximately  following  the  radius  of  the  cone,  are  carved  to  a 
greater  or  less  depth  into  the  lava  flows.     From  the  secondary  cone  around 


1  J.  S.  Diller  states  that  this  glacier  varies  from  1000  to  2000  feet  in  width,  and  has 
a  length  of  two  and  one-fifth  miles.  National  Geographic  Monographs,  vol.  1,  1805, 
p.  269.  _      . 


(II.Al'IKRH  OK  XOUTH    AMKHHA. 


I'l.ATK  6. 


SKETCH    MAP   OF    MOUNT   SHASTA,   CALIFORNIA,    by  Gilbert  Thompson. 

Scale :  1  iju'h  =  10,'.'00  teet. 


the 

ice 

on 

qui 

ti(i( 

Th( 

of. 

glai 

ing 


eral 

sun 

thai 

cre^ 

a  b 

al)n 

brai 

aim 

in  s 

the 

mel 

und 

of  t 

the 

of  \ 

A  t 

was 

nort 

hitt€ 

the 

cove 

four 

lowe 

the 

the 

upoi 

cann 

serie 

even 


GLACIERS   OF   NORTHERN   CALIFORNIA. 


67 


the  eastern  side  of  the  main  mass  are  only  occasional  fields  of  snow,  and 
ice  bodies  of  a  thousand  or  two  feet  long,  usually  quite  nan-ow  and  lying 
on  the  more  shaded  sides  of  the  ravines.  In  nature  and  texture  they  are 
quite  similar  to  the  true  glacial  ice,  possessing  in  all  cases  planes  of  stra- 
titication,  which  indicate  the  pressure  of  the  formerly  overlying  masses. 
There  is  little  doubt  that  all  the  scattered  snow  fields  that  in  the  months 
of  August  and  September  dapple  the  southern  slopes  are  the  relics  of 
glaciei's.  They  are  found  in  the  region  of  the  ancient  n^'ve,  but  extend- 
ing downward  into  what  was  formerly  the  zone  of  movement. 

"  Upon  reaching  the  eastern  side  we  fovind  in  a  deep  caflon  a  consid- 
erable glacier,  having  it«  origin  in  a  broad  n6\6  which  reached  to  the  very 
summit  of  the  peak.  The  entire  angle  of  this  glacier  can  hardly  be  less 
than  28°.  It  is  one  series  of  cascades,  the  whole  front  of  the  ice  being 
crevassed  in  the  most  interesting  manner.  Near  the  lower  end,  divided  by 
a  boss  of  lava,  it  forks  into  two  distinct  bodies,  one  extending  in  an 
abrupt,  rounded  face,  no  less  than  900  feet  in  height.  Below  this  another 
branch  extends  down  the  caflon  for  a  mile  and  a  half,  covered  throughout 
almost  in  entire  length  with  loatbj  of  stones  which  are  constantly  falling 
in  showers  from  the  caflon  walls  on  either  side.  Indeed  for  a  full  mile 
the  ice  is  only  visible  in  occasional  spots  where  cavities  have  been 
melted  into  its  body  and  loads  of  stones  have  fallen  in.  From  an  archway 
under  the  end  a  considerable  stream  flows  out,  milky,  like  the  watei-s 
of  the  Swiss  glacier  streams,  with  suspended  sand.  Following  around 
tlie  eastern  base  of  Shasta,  we  made  our  camps  near  the  upper  region 
of  vegetation,  where  the  forest  and  perpetual  snow  touch  each  other. 
A  third  glacier  of  somewhat  greater  extent  than  the  one  just  described 
was  found  upon  the  northeast  slope  of  the  mountain,  and  upon  the 
north  slope  one  of  much  greater  dimensions.  The  exploration  of  this 
latter  proved  of  very  great  interest  in  more  ways  than  one.  Receiving 
the  snow  of  the  entire  north  sloj^e  of  the  cone,  it  falls  in  a  great  field 
covering  the  slope  of  the  mountain  for  a  breadth  of  about  three  or 
four  miles,  reaching  down  the  caflons  between  four  and  five  miles,  its 
lower  edge  dividing  into  a  number  of  lesser  ice  streams  which  occupy 
the  beds  of  the  caflons.  This  mass  is  sufficiently  large  to  partake  of 
the  convexity  of  the  cone,  and  judging  from  the  depth  of  the  caflons 
upon  the  south  and  southeast  slopes  of  the  mountain,  the  thickness 
cannot  be  less  than  from  1800  to  2500  feet.  It  is  crevassed  in  a 
series  of  immense  chasms,  some  of  them  2000  feet  lon^^  by  30  and 
even  60  feet  wide.     In  one  or  two  places  the  whole  surface  is  broken 


58 


GLACIERS    UK    NOUTH    AMERICA. 


I 


'{■   ' 


with  concentric  systems  of  fissures,  and  these  are  invaded  by  a  set  ot 
radial  breaks  wliieh  shatter  the  ice  into  a  confusion  of  immense  blocks. 
Snow  bridges,  similar  to  those  in  the  Swiss  glaciei-s,  are  the  only 
means  of  crossing  these  chasms,  and  lend  a  spice  of  danger  to  the 
whole  examination.  The  region  of  the  terminal  moraines  is  quite 
unlike  that  of  the  Alps,  a  larger  portion  of  the  glacier  itself  being 
covered  with  loads  of  angular  debris.  The  whole  north  face  of  tlie 
mountain  is  one  great  body  of  ice  interrupted  by  a  few  sharp  lava 
ridges  whicli  project  above  its  general  level.  The  veins  of  blue  ice  and 
the  planes  of  stratification  were  distinctly  obseived,  but  neither  mouJinx 
nor  regular  dirt  bands  are  present.  Numerous  streams,  however,  flow 
over  the  surface  of  the  ice,  but  they  happen  to  pour  into  crevasses 
which  are  at  present  quite  wide. 

"  One  of  the  most  interesting  of  all  the  features  of  the  country  was, 
however,  the  clearly  defined  moraines  of  the  ancient  and  more  widely 
extended  glacier  system.  Nearly  the  whole  topography  of  the  lower 
part  of  the  cone  is  modified  by  the  deposition  of  glacial  material.  At 
an  elevation  ot  about  8000  feet  upon  the  northern  or  snowless  side 
of  the  mountain  is  a  gren*  plateau-like  terrace,  2500  or  3000  feet 
wide,  extending  around  one  .ilf  of  the  cone  and  composed  wholly  of 
morainal  material.  Besides  these,  long  straight  or  slightly  curved 
medial  moraines  jut  from  the  mountain  in  all  directions,  not  unfrequently 
descending  into  the  valley  for  several  miles." 

A  brief  account  of  the  glaciers  of  Mount  Shasta  was  contributed  by 
King  to  an  article  on  gravel  ridges  in  Merrimack  valley.  New  Hamp- 
shire, from  the  pen  of  G.  F.  Wright,^  in  which  special  attention  is  given 
to  the  moraines  now  forming  on  the  margins  of  the  glaciers  and  their 
resemblance  to  certain  glacial  deposits  of  New  England. 

In  the  account  of  an  ascent  of  Mount  Shasta,  published  in  the  reports 
of  the  Geological  Survey  of  California,"-^  of  which  Professor  J.  D.  Whitney 
was  director,  no  mention  is  made  of  the  existence  of  glaciers.  In  Profes- 
sor Whitney's  recent  work,  "  Climatic  Changes  of  Later  Geological  Time," 
previously  referred  to,  an  account  of  these  glaciers  is  introduced,  but  it 
contains  no  observations  in  addition  to  those  already  published  by  King. 

Observations  by  Gilbert  Thompson. — In  1882,  a  topographical 
survey  of  the  region  about  Mount  Shasta  was  begun  by  Gilbert  Thompson, 

1  Boston  Soc.  of  Nat.  Hist.,  Proc,  vol.  19,  1870,  p.  60. 

2  Vol.  1  (Geology),  pp.  332-351. 


(JLACIERS   OF    NORTHERN    CALIF(»RN1A. 


59 


(»f  the  U.  S.  Geological  Survey,  who,  at  my  request,  kindly  furnished  the 
following  notes  and  accompanying  sketch  map,  which  form  a  valuable 
addition  to  the  previous  descriptions  of  the  mountain  : 

"  During  a  portion  of  the  season  of  1883,  I  was  engaged  in  obtaining 
the  topographical  details  of  Mount  Shasta,  California,  and  take  {)leasure 
in  furnishing  such  information  as  I  can  concerning  the  glaciers  now 
existing  on  the  mountain. 

"  Mount  Shasta  is  a  volcanic  peak  situated  in  latitude  41°  24'  30", 
longitude  122°  11'  34".  Its  altitude,  as  determined  by  the  U.  S. 
(ieological  Survey,  is  14,350  feet.  It  stands  alone  and  has  no  connection 
with  neighboring  mountains,  none  of  which  within  a  radius  of  40  miles 
attain  two-thirds  its  height.  The  greatest  length  of  its  northwest  slope, 
terminated  by  Little  Shasta  valley,  which  has  an  altitude  of  3000  feet,  is 
16  miles.  The  southwest  slope  reaches  Elk  flat  and  descends  over  10,000 
feet  in  eight  miles.  The  highest  divide  to  the  northwest  is  six  miles 
distant  and  has  an  altitude  of  0000  feet.  The  divide  of  the  Sacramento 
liver,  ten  miles  to  the  westward,  is  3500  feet  above  the  sea.  The 
ordinates  from  the  summit  to  the  contour  of  8000  feet  will  vary  from 
three  to  four  miles  in  length.  The  point  where  the  timber  growth 
receives  its  first  check  is  at  an  elevation  of  8200  feet ;  the  last  tree, 
however,  so  diminutive  as  hardly  to  cover  the  palm  of  one's  hand,  was 
found  at  the  altitude  of  10,130  feet.  Mount  Shasta  attracts  the  attention 
at  a  distance  of  over  100  miles,  and  from  nearer  points  the  solemn  repose 
and  grandeur  of  its  isolation  are  impressive. 

"  The  glacier's  about  the  summit  of  Mount  Shasta  do  not  exist  under 
the  protection  of  sheltering  cliffs  or  in  the  depths  of  cafions,  but  occur  on 
the  flanks  of  the  mountains  and  are  exposed  for  three-fourths  of  the 
day  to  the  full  power  of  the  sun.  The  streams  that  have  their  origin  in 
the  melting  of  the  snow,  appear  suddenly  at  the  foot  of  the  mountain  as 
rushing  currents  loaded  with  silt :  these  subside  during  the  latter  part  of 
the  night  and  leave  pools  of  clear  water,  which  also  gradually  disap})ear. 
The  water  again  reaches  the  surface  in  unexpected  places  many  miles 
distant  as  immense  springs.  The  stream  channels  are  thus  flooded  once 
a  day  during  the  summer ;  and  after  the  first  snow,  which  occurs  about 
the  first  of  October,  no  more  water  descends  from  the  snow  fields. 

"  Besides  a  few  snow  banks  that  last  throughout  the  year  and  a  few 
small  glaciers  in  the  shadow  of  protecting  cliffs,  there  are  five  ice  streams 
which  especially  invite  attention.  With  the  exception  of  the  Whitney 
glacier,  which   was   named  in  honor  of  the  former   state  geologist  of 


w 


i     J    i 


60 


GLACIERS   OF   NORTH   AMERICA. 


H 
II 

■» 
hhh 

» 

.1     ■  1 

r 

California,  these  have  been  designated  by  the  following  Wintun  names  : 
Konwakiton  (mud  glacier),  Wintun  (Indian  tribal  name),  Hotlum 
(Steeproek),  and  Bulam  (great). 

"  The  Konwakiton  [McCloud]  glacier  is  situated  on  the  southeastern 
slope  and  fills  a  basin  at  the  head  of  a  deep  and  rugged  caflon.  Its  foot 
is  at  the  altitude  of  about  12,000  feet,  and  from  beneath  it  a  strong 
stream  flows  down  the  gorge,  at  times  di8a[)pearing  Ixiueath  a  flooring 
of  ice,  covered  with  l)oulders  and  debris  derived  from  the  walls  that 
overshadow  it.  On  reference  to  the  topographic  sketch  [Plate  3]  it  will 
be  seen  that  this  stream  falls  in  a  cascade  in  the  upper  portion  of  the 
caflon  ;  at  a  lower  altitude  it  forms  another  beautiful  waterfall  about  400 
feet  in  height.  The  surface  of  this  glacier  has  an  area  of  about  320,000 
scjuare  yards.  When  making  the  ascent  by  Sisson's  southern  foot-trail, 
just  as  tlie  weary  climber  turns  the  '  Red  rocks,'  at  13,000  feet  altitude, 
ha  is  forced  to  make  a  short  detour  on  the  n6v6  of  this  glacier,  which  is 
'jsually  separated  from  the  wall  of  rock  by  a  deep  crevasse.^ 

"  Til?  Wintun  glacier  has  an  area  of  about  2,000,000  square  yards,  an 
average  breautu  of  1000  yards,  and  is  3400  yards  in  length.  In  its 
course  it  flows  over  two  precipices  and  becomes  greatly  broken  by  curving 
crevasses,  inclosing  huge  rocks  and  pinnacles  of  ice.  These  are  veritable 
ice  cascades  of  no  mean  proportions,  and  afford  details  of  glacial  structure 
of  great  beauty  and  interest.  Near  its  teiininus  the  glacier  forms  a  true 
ice  stream  confined  by  caflon  walls,  and  finally  terminates  in  an  ice  foot 
several  hundred  feet  high  which,  as  indicated  in  the  accompanying  sketch, 
is  furrowed  by  numerous  stream-cut  channels.  A  close  approach  to  the 
ice  wall  is  dangerous  because  of  the  stones  and  morainfil  matter  that  at 
least  in  summer  are  constantly  falling  as  the  ice  melts.  The  glacier 
terminates  at  an  altitude  of  about  8000  feet,  and  froni  It  flows  a 
considerable  stream  which  is  always  loaded  with  mud  and  silt.  Some 
distance  below  the  terminus  this  yellow  stream  forms  a  cascade  fully 
400  feet  in  height.     The   walls  of   the  caflon  occupied  by  the  lower 

1  In  describing  this  glacier  .T.  S.  Diller  states  tliat  tlie  morainal  material  upon  its 
borders  is  small,  and  yet,  of  all  the  glaciers  about  Mount  Shasta,  it  is  the  only  one  which  has 
left  a  prominent  record  of  important  changes.  During  a  former  period  it  was  over  five 
miles  in  length  and  occupied  an  area  of  at  least  seven  square  miles,  being  twenty  times  its 
present  size.  With  this  exception,  there  are  no  records  upon  the  slopes  of  Shasta  that  any 
of  the  existing  glaciers  were  ever  very  much  larger  than  at  present. 

The  existing  glaciers  on  Mount  Shasta  are  but  remnants  of  far  larger  Ice  streams  that 
descended  from  the  mountain  in  Pleistocene  lime,  and  left  large  and  well-characterized 
moraines  on  its  southwestern  side  some  ten  miles  from  the  summit.  National  Geographic 
Monographs,  vol.  1,  1895,  pp.  262,  263. 


GLACIERS   OP   NORTHERN   CALIFORNIA. 


61 


portions  of  this  glacier,  in  common  with  nearly  all  the  flunks  of  Mount 
Shasta,  are  sombre  in  color  and  unpicturesque ;  below  the  falls,  however, 
thure  are  many  points  of  view  that  will  hold  the  attention  and  excite  the 
enthusiasm  of  the  traveler. 

"The  Hotlura  glacier*  is  situated  northward  of  the  Wintun,  and 
separated  from  it  by  a  series  of  narrow  and  precipitous  spurs.  On  the 
north  it  is  bounded  by  a  narrow  crest  of  rock  which  at  first  glan(!c  might 
be  tiiken  to  be  a  medial  moraine.  The  foot  of  this  £  iacier  ends  in  an  arc 
of  terminal  moraines,  at  an  altitude  of  10,500  feet,  which  at  certain 
points  rests  upon  the  lower  portion  of  the  ice.  A  thousand  streams 
formed  by  the  melting  glacier  find  their  way  over  and  tlirough  the  debris 
Held,  and  render  it  a  treacherous  terrain  to  explore. 

"  Through  the  n6v6  of  the  Hotlum  glacier  two  ice  streams  may  be  said 
to  flow,  one  of  which,  in  crowding  past  two  rocky  buttresses,  is  broken 
into  ])innacles  of  ice  50  to  60  feet  in  height,  which  are  of  a  pearly  blue 
tint,  and  present  a  fantastic  and  beautiful  spectacle.  Tliu  crevasses 
])elow  the  rocks  are  very  deep  and  wide.  Associated  with  them  are  wells 
of  water  of  great  depth  having  a  translucent  blue  color;  these  were  oval 
in  sliape,  the  longer  axis  being  in  the  direction  of  the  flow  of  the  glacier. 
Tiie  glacier  is  2500  yprds  in  length,  and  covera  an  area  of  about  3,200,000 
square  yards. 

''  The  Bulam  glacisr,  situated  on  the  northern  face  of  the  mountain, 
indicates  by  the  magnitude  of  its  terminal  moraine  tliat  it  carries  greater 
floods  of  debris  than  any  of  its  associated  ice  streams.  At  the  time  of 
my  examination  the  foot  of  this  glacier  had  retreated  to  a  considerable 
distance  from  the  terminal  moraines,  and  was  divided  into  two  flows. 
The  first  crevasse  in  this  glacier  occurs  at  an  elevation  of  about  11,000 
feet,  and  is  of  great  width,  length,  and  depth.  From  this  rent  to  the 
terminus  of  the  glacier  the  ice  is  oroken  into  rough  blocks,  and  is  deeply 
seamed  with  fissures.  The  Bulam  glacier  is  about  3200  yards  in  length, 
and  approximately  1,800,000  square  yards  in  area.  The  crest  of  the 
terminal  moraine  skirting  its  lower  limit  had  an  altitude  of  10,000  feet. 

"Separated  from  Bulam  glacier  by  a  steep,  narrow  ridge,  as 
represented  on  Plate  5,  is  Whitney  glacier,  a  photograph  of  which  is 
given  in  Fig.  A,  Plate  6.  This  is  the  most  typical  ice  stream  on  the 
mountain,  and  originates  in  the  n6v^  lying  oii  the  table  at  the  summit  of 

*  The  surface  of  the  Hotlum  glacier  Ls  convex  from  side  to  side,  >>nd  its  widfi  (1.23  miles) 
is  almost  as  great  as  its  length  (1.62  miles).  J.  S.  Diller,  National  Geographic  Monographs, 
1895,  vol.  1,  p.  261. 


rwm.TT- 


IS- 


•r 


62 


GLACIERS   OF   NORTH    AMERICA. 


the  peak.  "Whitney  glacier,  in  crowding  past  the  east  base  of  Shastina 
crater,  which  it  has  partially  undermined,  occasions  a  constant  falling  of 
rocks  and  debris,  and  becomes  broken  into  a  multitude  of  blocks,  whicli 
are  reunited  as  the  stream  flows  on.  The  Whitney  glacier  is  3800 
yards  in  length,  and  covers  an  area  of  1,900,000  s(juare  yards  ;  in  Octo- 
ber, 1883,  its  terminus  was  at  an  elevation  of  9500  feet  above  the  sea.^ 

"A  careful  examination  of  some  of  the  ice  bodies  on  the  western  flank 
of  Mount  Shasta  would  perhaps  lead  to  their  being  classed  as  glaciers  of 
secondary  magnitude ;  they  occur  on  steep  slopes  at  high  altitudes,  and 
sill  are  over  700  feet  in  length. 

"At  the  time  of  Mi.  King's  examination,  in  1870,  Mr.  Watkins,  of 
Siui  Francisco,  obtained  a  number  of  i)liotographs  of  Mourit  Shasta,  from  a 
careful  examination  of  which  I  conclude  that  ther j  was  more  snow  on  the 
mountain  when  they  were  taken  than  at  the  time  of  my  visit  in  1883 ; 
this  decision  is  also  sustained  by  the  statements  of  the  residents  in  the 
vicinity."  ^ 


Mount  Rainier. 

(A  sketch  map  of  the  glaciers  on  Mt.  Kalnier  forms  Plate  7.) 

In  the  Proceedings  of  the  California  Academy  of  Sciences  for  Mareli 
6,  1871,  it  is  stated  by  Professor  George  Davidson  that  Lieutenant,  after- 
ward General,  August  V.  Kautz  attempted  the  ascent  of  Mount  Rainiei- 
in  1857,  but  found  his  way  barred  by  a  great  glacier.  So  far  as  can  l)e 
ascertained  no  published  account  of  Kautz's  observations  has  appeared. 
but  from  Davidson's  statement  it  seems  that  he  first  reported  the  exist- 
ence of  living  glaciers  in  the  United  States.  An  abstract  of  Kautz's 
manuscript  account  of  his  excursion  is  given  by  S.  F.  Emmons  ^  iii  uii 

1  "  The  most  striking  feature  of  Whitney  glacier,  and  that  which  is  of  the  greatest 
interest  from  a  geologic  point  of  view,  is  the  debris  it  brings  down  tlie  mountain  and  pilt  s 
ui>  making  a  hirge  terminal  moraine  at  its  lower  ei.l.  This  moraine  appears  to  be  fully  a 
mile  in  length,  measured  down  the  slope  of  the  mountain.  Its  apparent  length  is  nuK  li 
greater  than  the  real,  however,  from  the  fact  that  the  glacier  ice  extends  far  beneath  the 
covering  of  detritus.  It  is  so  huge  a  pile  of  light-colored  debris,  just  above  the  timber  line, 
that  it  is  plainly  visible  from  afar."  J.  S.  Uillei,  National  Geographic  Mouograplia,  vol.  1, 
1896.  pp.  259,  260. 

'^  Since  the  book  before  you  was  written,  an  instructive  monograph  on  "  Mt.  Shasta,  a  Typi- 
cal Volcano,"  had  been  published  by  J.  S.  Diller,  which  includes  an  account  cf  the  glaciers 
described  above.  The  book  referred  to  is  one  of  a  series  entitled  "  National  Geographic 
Monographs,"  publish-  1  under  the  auspices  of  the  National  Geographic  Society. 

8  Journal  of  the  ^luierican  Geographical  Society,  vol.  9,  p.  46. 


I  if 


fl"l!|P 


GLAriERs  OF  Xoicrii  Amkkh  .\ 


Pi.ATF  n. 


Fig.    a.  — WHITNEY    GLACIER,    MOUNT    SHASTA,    CALIFORNIA 


Fig    B.  — summit   OF   MOUNT   RAINIER,    WASHINGTON. 
.Che  head  of  Emmons  Glacier.    Little  Tahonia  ami  Gibraltar     .1  the  left 


I'    1 


■tv  :r'^-'         i 


GLACIERS   OF   NORTHERN   CALIFORNIA. 


^^ 


address  before  the  American  Geographical  Society,  but  it  contains  little 
information  of  special  interest  concerning  the  glacier  seen. 

Observations  by  S.  F.  Emmons.  —  The  addr-iss  referred  to  above, 
entitled  "  The  Volcanoes  of  the  Pacific  Coast  of  the  United  States,"  is 
devoted,  mainly  to  a  description  of  an  ascent  of  Mount  Rainier  by 
Emmons  in  October,  1870,  and  includes  many  observations  on  the 
glaciers  examined  during  his  survey  of  the  mountain.  A  more  detailed 
account  of  these  glaciers  was  contributed  by  Emmons  to  an  article  by 
King  ^  on  the  glaciers  of  the  Pacific  slope,  and  I  shall  quote  from  this  in 
preference  to  the  more  popular  essay  read  before  the  Geographical  Society : 

"The  glaciers  of  Mount  Tachoma  [Tacoma],  or  Rainier,  as  it  is 
more  commonly  called,  form  the  principal  sources  of  four  important 
rivers  of  Washington  Territory,  viz.:  the  Cowlitz,  which  flows  into  the 
Columbia,  and  the  Nisqually,  Puyallup,  and  White  rivers,  Avhich  empty 
into  Puget  sound.  .  .  .  The  summit  of  Tachoma  is  formed  by  three 
peaks,  a  southern,  an  eastern,  and  a  norihwestern ;  of  these  the  eastern 
is  the  highest ;  those  on  the  south  and  nortliwest,  being  apparently  a 
few  hundred  feet  lower,  are  distant  about  a  mile  and  a  half  to  two  miles 
from  this,  and  separated  by  deep  valley  s.  The  eastern  peak  which  would 
seem  to  have  formed  originally  the  middle  of  the  mountain  mass,  is  a 
crater  about  a  quarter  of  a  mile  in  diameter  of  very  perfect  circular  form. 
Its  sides  are  bare  for  about  sixty  feet  from  the  rim,  below  which  they  are 
covered  by  a  nev^  having  a  slope  of  28*^  to  31°.  This  nevd,  extending 
from  the  sliouldei's  of  the  southwestern  peak  to  those  of  the  northern,  a 
width  of  several  miles,  descends  to  a  vertical  distance  of  about  2000  feet 
below  the  crater  rim,  an  immense  sheet  of  white  granular  ice  having  the 
general  form  of  the  mountain  surface,  and  broken  only  by  long  transverse 
crevasses,  one  of  those  observed  being  from  one  to  two  miles  in  length ; 
it  is  then  divided  up  by  the  several  jutting  rock  masses,  or  shoulders  of 
the  mountain,  into  the  Nisqually,  Cowlitz,  and  Wliite  River  glaciers,  fall- 
ing in  distinct  ice  cascades  for  about  3000  feet  at  very  steep  angles,  which 
sometimes  approach  the  perpendicular.  From  the  foot  of  these  cascades 
flow  the  glaciers  proper  at  a  more  gentle  angle,  growing  narrower  and 
sinking  deeper  into  the  mountain  as  they  descend.  From  the  inter- 
vening spurs,  which  slope  even  more  gradually,  they  receive  many 
tributary  glaciers,  while  some  of  these  secondary  glaciers  form  inde- 
pendent streams  which  only  join  the  main  river  many  miles  below  the 
end  of  the  glaciers. 

*  American  Journal  of  Science,  Third  Series,  vol.  1,  1871,  p.  161. 


64 


GLACIERS   OF   NORTH   AMERICA. 


"  The  Nisqnally,  the  narrowest  of  the  three  main  glaeierg  ai#/>ve 
tioned,  has  the  most  sinuous  couree,  vtirying  in  direction  ft(rm  uoalfclNsit 
to  south,  while  its  lower  extremity  is  somewhat  west  /  ncmi^  of  ^' 
main  peak ;  it  receives  most  of  its  tributaries  from  the  «p»i  '  I//  tttt  Mmt^ 
and  has  a  comparatively  regular  slope  iu  its  whole  k^ngth  ii&Ur^  the 
cascade.  There  are  some  indications  of  dirt  band.^  on  >fo  ^Mrfwm  Wh^^tt 
seen  from  a  considerable  elevation.  Toward  its  low* -■  en4  A  i*  vdv 
much  broken  up  by  transverse  and  longitudinal  crevasses ;  .*)»»  is  <. 
the  fact  that  it  has  here  cut  through  the  more  yielding  strata  f/f  v^/^«#ii^/ 
rock,  and  come  upon  an  underlying  and  unconformaWe  mi*m  (A  M/^nit*-. 
The  ice  front  [Fig-  B,  Plate  6]  at  its  base  is  about  500  feet  in  height,  and 
the  walls  of  lava  which  bound  its  sides  rise  from  1000  to  1500  feet  above 
the  surface  of  the  ice,  generally  in  sheer  precipi*  es. 

"  The  bed  of  the  Cowlitz  glacier  is  generally  parallel  to  that  of  the 
Nisqually,  though  its  curves  are  less  marked ;  the  ice  cascades  in  which 
each  originates  fall  on  either  side  of  a  black  cliff  of  bedded  lava  and 
breccia  scarcely  a  thousand  feet  in  horizontal  thickness,  while  the  mouths 
of  the  glaciers,  if  I  may  be  allowed  the  expression,  are  about  three  miles 
apart.  From  the  jutting  edge  of  this  cliff  hang  enormous  icicles  from  75 
to  100  feet  in  length.  The  slope  of  this  glacier  is  less  regular,  being 
broken  by  subordinate  ice  cascades.  Like  the  Nisqually,  its  lower 
extremity  stretches  out,  as  it  were,  into  the  forest,  the  slopes  on  eithci- 
ade,  where  not  too  steep,  being  covered  with  the  mountain  tir,  Picea 
nohilis,  for  several  hundred  feet  above  the  level  of  the  ice,  while  the 
Pinns  flexilis  grows  at  least  2000  feet  higher  than  the  mouth  of  the 
glacier. 

"  The  general  course  of  this  glacier  is  south,  but  at  its  extremity  it 
bends  to  the  eastAvard,  apparently  deflected  from  its  course  by  a  cliff  of 
older  felsitic  rock  more  resisting  than  the  lava.  The  consequence  of  this 
deflection  is  a  predominance  of  longitudinal  over  transverse  crevasses  at 
this  point,  and  an  unusually  large  moraine  at  its  western  side,  whi(;h 
rises  several  hundred  feet  above  the  surface  of  the  glaciers,  and  partakes 
of  the  character  of  both  lateral  and  terminal  moraines  ;  the  main  medial 
morainfi  of  a  glacier  joins  this  near  its  lower  end.  [The  crevassed  and 
moraine-covered  surface  of  Cowlitz  glacier  is  shown  in  Fig.  A,  Plate  8.] 
This  medial  moraine  proceeds  from  the  cliff  which  bounds  the  ice- 
cascade  source  of  ihe  glacier  on  the  north,  and  brings  down  a  dark 
porous  lava  which  is  onh'  found  high  up  on  the  mountain  near  the  crater. 
The  position  of  the  medial  moraine  on  the  glac'  "\^  indicate  that  at 


'<^/^ 


i  lower 
n  either 

Picea 
lile  the 

of  the 


J3 

a 

o 

a 
o 


o 

u 

a 
a. 
< 


rtiw* 


>! 


GLACIERS   OF   NORTHERN   CALIFORNIA. 


66 


least  half  its  mass  came  from  the  spur  on  the  east,  which  is  probably  the 
case. 

"  This  spur,  comprehending  the  whole  mass  between  the  Cowlitz  and 
White  River  glaciers,  has  the  shape  of  a  triangle,  whose  apex  is  formed 
by  a  huge  pinnacle  of  rock  which,  as  its  bedding  indicates,  once  formed 
part  of  the  CwSt  of  the  mountain,  but  now  stands  isolated,  a  jagged  peak 
rising  about  3000  feet  above  tlie  glaciera  at  its  foot,  so  steep  that  neither 
ice  nor  snow  rests  upon  it.  One  of  the  tributarias  to  the  Cowlitz  glacier 
from  this  spur  brings  down  with  it  a  second  medial  moraine,  which  is 
traceable  to  the  mouth  of  the  glacier,  though  in  general  these  tributary 
glaciers  bring  no  medial  moraines. 

"On  the  eastern  slopes  of  this  spur,  between  the  two  above-named 
glaciers,  spread  secondary  gl.aciera  frequently  of  great  width,  but,  owing 
to  the  limited  height  of  their  initial  points,  of  inconsiderable  length. 
These  end  generally  in  perpendicular  cliffs  overhanging  the  rocky  amphi- 
theatres at  the  heads  of  the  smaller  streams  which  flow  eastward  into  the 
Cowlitz.  Looking  up  from  the  bottom  o''  one  of  the^^"  amphitheatres  one 
sees  a  semicircular  wall  of  nearly  2000  feet  of  sheer  rock,  surmounted 
by  about  500  feet  of  ice,  from  under  wliich  small  streams  of  water  issue, 
falling  in  silvery  cascades  onto  the  green  bottom  below. 

"  A  ridge  of  high  jagged  peaks  connects  this  spur  with  the  main  range 
of  the  Cascade  mountains  in  the  east,  and  foi-ms  the  waterahed  between 
the  White  and  Cowlitz  rivre.  From  the  connecting  saddle  one  can  look 
northward  across  the  brink  of  six  glaciere,  which  all  contribute  to  the 
White  river;  of  these  the  fia»t  four  come  from  tbe  triangular  spur 
already  mentioned,  and  are  of  comparatively  little  extent.  The  first  two 
are,  however,  interesting  from  the  veined  structure  which  they  exhibit ; 
they  both  originate  in  an  irregularly  oblong  basin,  having  the  shape 
somewhat  of  an  inclined  ellipse,  turning  on  its  long  diameter,  the  outlets 
of  the  glacier  being  opposite  the  foci.  Seen  from  a  r^iyii  point  the  veins 
form  concentric  lines  generally  parallel  to  the  side  f  the  ijasin ;  the 
ends  of  those  towards  the  center  gradually  l)end  r(/U..d  until  they  join 
together  in  form  of  a  figure  S,  and  finally  just  above  the  outlets  form 
two  small  ellipses.  They  thus  constantly  preserve  a  direction  at  right 
angles  to  that  of  the  pressure  exerted  downward  by  the  movement  of  the 
ice  mass,  and  upward  by  the  resistance  to  this  movement  of  the  rock 
mass  between  the  two  outlets. 

"  The  main  White  River  glacier,  the  grandest  of  the  whole,  pours 
straight  down  from  the  rim  of  the  crater  in  a  northeasterly  direction,  and 


r 


66 


GLACIEUS   OF   NORTH   AMERICA. 


1  i        i 

!    J    -     i 


'i      J 


tl 


pushes  its  „xtremity  farther  out  into  the  valley  than  any  of  the  others. 
Its  greatest  width  on  the  steep  slope  of  the  mountain  must  be  four  or  live 
miles,  Harrowing  towards  its  extremity  to  about  a  mile  and  a  half ;  its 
length  can  be  scarcely  less  than  ten  miles.  The  great  eroding  [)ower  of 
glacial  ice  is  strikingly  illustrated  in  this  glacier,  whic)i  seem.s  lu  have 
cut  down  and  carried  away  on  the  northeastern  side  of  the  mountain,  fully 
a  third  of  its  mass.  The  thickness  of  rock  cut  away,  as  showii  by  the 
Avails  on  either  side,  and  the  isolated  peak  at  the  head  of  the  triangular 
spur,  in  which  the  bed'ling  of  the  successive  flows  of  lava  is  very  regular 
and  conftn-mable,  may  be  estimated  at  somewhat  over  a  mile.  Of  the 
thickness  of  the  ice  of  the  glacier  I  have  no  data  for  making  estimates, 
though  it  may  probably  be  reckoned  in  thousands  of  feet. 

"  It  has  two  principal  medial  moraines,  which,  where  crossed  by  us, 
formed  little  mountain  ridges  having  peaks  nearly  100  feet  high-.  The 
sources  of  these  moraines  are  cliffs  on  the  steeper  mountain  slope,  which 
seem  mere  black  specks  in  the  great  wdiite  field  above  ;  between  these  are 
great  cascades,  and  below  immense  transverse  crevasses,  which  we  had  no 
time  or  means  to  visit.  The  surface  water  flows  in  rills  and  brooks  on 
the  lower  portion  of  the  glacier,  and  moidins  are  of  frequent  occurrence. 
We  visited  one  double  moulin  where  t'.vo  brooks  poured  into  two  circular 
wells,  each  about  ten  feet  in  diameter,  joined  together  at  the  surface  but 
separated  below ;  Ave  could  not  approach  near  enough  the  ii(\gQ  to  see  the 
bottom  of  either,  but,  as  stones  thrown  in  sent  back  no  sound,  judged 
they  must  ^e  very  deep. 

"  This  glacier  forks  near  the  foot  of  the  steeper  mountain  slope,  and 
sends  off  a  branch  to  the  northward,  which  forms  a  large  stream  flowing 
down  to  join  the  main  stream  fifteen  or  twenty  miles  below.  Looking 
down  on  this  from  a  high,  overhanging  peak,  we  could  see,  as  it  were 
under  our  feet,  a  little  lake  of  deep  blue  water,  about  an  eighth  of  a  mih' 
in  diameter,  standing  in  the  brown  gravel-covered  ice  of  the  end  of  the 
glacier.  On  the  back  of  the  rocky  spur  which  divides  these  tv/o  glaciers, 
a  secondary  glacier  has  scooped  out  a  basin-shaped  bed,  and  sends  dcwii 
an  ice  stream  having  all  the  characteristics  of  a  true  glacier,  but  its 
ice  disappears  several  miles  above  the  mouths  of  the  large  glaciers  on 
either  side.  Were  nothing  known  of  the  movements  of  glaciers,  an 
instance  like  this  would  seem  to  afford  sufficient  evidence  that  sucli 
movement  exists,  and  that  gravity  is  the  main  motive  power.  From  oui' 
northern  and  southern  points  we  could  trace  the  beds  of  several  large 
glaciers  to  the  Avest  of  us,  Avhose   upper  and  loAver  portions  only  were 


(II.AdKHS  OK   NilKTll    AMKHIt  A. 


V\    \TK   A 


Fig.  a.  — surface  OF  COWLITZ   GLACIER,   MOUNT   RAINIER,   WASHINGTON, 


Fig    B.       ICE   CAVE  AT   THE   END  OF   NISQUALLY   GLACIER,   MOUNT   RAINIER. 

WASHINGTON 


GLACIERS   OF   NORTHERN   CALi5C'7NIA 


67 


visible,  the  main  body  of  the  ice  lying  hidden  by  the  high  intervening 
spurs. 

"  Ten  large  glaciers  observed  by  us,  and  at  least  half  as  many  more 
hidden  by  the  moun^aiij  from  our  view,  proceeding  thus  from  an  isolated 
peak,  formed  a  moM  remarkable  system,  and  one  worthy  of  a  careful  ard 
detailerl  study." 

A  graphic  ac^^ount  of  nn  ascent  of  "Takhoma"  [Rainier]  was  pub- 
lished in  the  Atlantic  Montiuy^by  Geneml  Hazar'  Stevens,  who  ascended 
tlifi  peak  in  August,  1H70.  Frequent  reference!*  are  made  in  ihis  essay 
to  the  numerous  ice  streams  that  originate  on  the  mountain,  but  no 
detailed  ac(  ount  of  glacial  phenomena  is  presented. 

Recent  Ascents.  —  Since  the  pioneer  ascents  of  Mount  Rainier 
described  above  were  made,  the  mountain  has  Ijeen  ascended  by  many 
tourists,  and  now  that  the  route  to  the  summit  is  familiar  il  appears  that 
the  climb  is  not  so  difficult  as  at  first  supposed.  Several  excursion  parties 
have  succeeded  in  reaching  the  summit,  and  have  even  passed  the  night 
in  the  crater  at  the  top.  Ladies  have  been  members  of  these  expeditions 
and  have  experienced  no  great  fatigue  or  hardship  from  tl.  ir  ascent.  A 
graphic  and  entertaining  account  of  one  of  the  nore  recent  ascents,  by 
Rev.  Ernest  C.  Smith,  in  which  the  luxuriance  and  beauty  of  the 
vegetation  clothing  the  lower  slopes  of  the  ma' jstic  peak  are  contrasted 
with  the  barrenness  and  desolation  of  die  snow  fields  at  the  summit, 
appeared  in  Appalachia,^  and  is  accompanied  by  a  number  of  excellent 
photographs  of  glaciers.  • 

The  magnificence  of  the  scenery  about  Mount  Rainier  and  in  the 
neighboring  Cascade  mountains,  as  well  as  a  widely  spread  popular 
interest  in  the  glaciers  and  other  natural  features  of  that  region,  has  led 
to  an  effort  to  have  Congress  set  aside  a  reservation  to  be  known  as  the 
Washington  National  Park,  and  embi.>,cing  an  area  of  about  25  miles 
square,  of  which  the  summit  of  Mount  Rainier  is  the  culminating  point. 

Mount  Hood.     -,.-./'S:^' ^'      ['"I '-'■■"'"'[  ■P:;..C 

In  August,  1866,  Professor  A.  Wood  ascended  Mount  Hood,  and 
later  in  the  year  gave  a  short  account  of  his  observations  before  the  Cali- 
fornia A.cademy  of  Sciences.^   During  his  ascent  he  encountered  chasms  of 

1  Vol.  38,  1876,  p.  513.  a  Vol.  7,  1894,  pp.  186-205. 

»  Proceedings,  vol.  3,  p.  292. 


Kn 


IMAGE  EVALUATION 
TEST  TARGET  fMT-3< 


T 


1.0 


I.I 


L25  i'U 


.*/' 

t/ 


1^ 

1.6 


Sciences 
Corporation 


33  WfST  MAIN  STREET 

WEBSTER,  N.Y.  14580 

(71*)  ira-ASOS 


w 


1 

II 


G8 


GLACIERS    OF   NOllTU    A.VEKICA, 


f  ini 


invisible  depth  in  solid  blue  ice,  in  which  the  rush  of  subglacial  streams 
could  be  heard.  Fron.  the  summit  of  the  peak  a  deep  cafion,  eroded 
in  the  steep  southeast  slope  of  the  mountain,  was  seen  to  be  partly 
filled  by  a  glacier.  Both  terminal  and  lateral  moraines  could  be  dis- 
tinguished on  the  surface  of  the  ice,  and  a  torrent  of  water  issued  from 
its  terminus. 


Observation  by  Arnold  Hngrut^*  —  In  a  contribution  to  King's  article 
on  the  glaciers  of  the  Pacific  coast,*  already  referred  to,  the  follo"  'ng  ac- 
count of  the  existing  glaciers  of  ]Mount  Hood  is  given  by  Arnold  Hague: 

"  The  cra.<er  [of  Mount  Hood]  is  nearly  one-half  a  mile  wide  from 
east  to  west.  The  wall  upon  the  inner  side  rises  above  the  snow  and  ice 
filling  the  basin  some  450  feet,  while  upon  the  outer  side  it  falls  oft" 
abruptly  for  2000  feet.  This  rim  of  the  crater  is  very  narrow ;  in  many 
places  the  crest  is  not  more  than  2  feet  wide. 

"  Three  distinct  glaciers  have  their  origin  in  this  basin,  each  the 
source  of  a  stream  of  considerable  size ;  the  glaciers  of  the  White,  the 
Sandy,  and  the  l^ittle  Sandy  rivers. 

"  The  White  River  glacier  heads  on  the  eastern  side  of  the  crater  and 
extends  in  a  southeasterly  direction.  It  is  barely  a  quarter  of  a  mile 
wide  at  the  head,  and  about  2  miles  long,  extending  500  feet  below  the 
line  of  the  timber  growth  upon  the  side  of  the  mountain. 

"Near  the  top  of  the  crate"  a  broad  transverse  crevasse  cut-?  entirely 
across  the  glacier.  Freshly  fallen  snow  overhangs  the  perpendicular  walls 
of  ice,  making  it  exceedingly  dangerous  to  approach.  At  one  point  only 
the  fissure  may  be  crossed  by  an  ice  bridge.  Further  down  the  slope  of 
the  glacier  transverse  crevasses  are  of  frequent  occurrc^ice,  running  nearly 
parallel  with  each  other ;  most  of  them  are,  however,  quite  narrow.  One 
broad  chasm  presented  clean,  sharply  cut  vertical  sides,  for  nearly  200 
feet  in  depth,  of  clear  deep-blue  ice.  Marginal  crevassea,  ice  caves,  and 
caverns  occur.  Many  of  the  latter  are  very  beautiful  and  afford  fine 
opportunities  for  the  study  of  the  laminated  and  veined  structure  of 
glacial  ice. 

"  Very  many  of  the  phenomena  attendant  upon  glaciers  elsewhere 
may  be  observed  here.  The  terminal  and  lateral  moraines  are  well  marked 
and  extensive.  Medial  moraines,  however,  do  rot  appear,  because  the 
glacier  has  no  tributaries.  Glacial  grooving,  glacial  debris,  and  boulders 
are  quite  characteristic. 

1  American  Journal  of  Sclsnce,  Third  Series,  vol.  1,  1871,  p.  165. 


fil.AI  IKItS  UK  Nlllll'll    .\mi:kii  a. 


i'r.ATK  0. 


■  i 


FiG.    A.— SUMMIT   OF    MOUNT    BAKER,   WASHINGTON. 


Fig.   B.  — CREVASSES,   JL' ECELLEWAET   GLAr,ER.   CANADA. 
(Photograph  by  \Vm.  Notniau  Si  Son.) 


riv 
the 
feci 
coi 
are 


the 
sail 
cha 
we£ 
pov 
con 
Col 


it  u 
the 
fror 
trac 

big] 
cut 
itou 
quit 

i\Ioi 
^lac 
cutt: 
The 
that 
anci( 
obse 


Bakt 
Magi 


GLACIEaS  OF   NORTHERN   CALIFORNIA. 


69 


"The  glacier  of  iSandy  river  is  separated  from  that  of  the  White 
liver  by  a  high,  bare  ridge,  standing  boldly  up  above  the  ice  and  dividing 
the  crater  into  two  parts.  The  glacier  descends  to  the  southwest.  It  is 
fed  by  the  snow  and  ice  of  a  somewhat  larger  area  of  country,  and  is 
considerably  broader  than  the  glacier  of  White  river.  In  length  they 
are  about  equal. 

"  An  immense  amount  of  glacial  debris  must  be  annually  carried  down 
the  streams  whose  waters  are  heavilj  charged  with  fine,  light  gray  trachytic 
sand,  brought  down  from  above  by  this  moving  mass  of  ice.  The 
character  of  the  rock,  a  brittle,  porous  trachytic,  is  such  that  under  the 
wearing  action  of  the  glacier  it  would  be  easily  eroded  and  ground  to  fine 
powder.  The  very  extensive  accumulation  of  sand  banks,  which  are 
constantly  forming  at  the  mouth  of  the  stream  where  it  empties  into  the 
Columbia  river,  bears  ample  evidence  of  the  fact. 

"  The  Little  Sandy  river,  a  tributary  of  the  main  stream,  with  which 
it  unites  a  few  milef5  below  the  base  of  the  mountain,  has  its  pource  in 
the  third  glacier  which  is  formed  on  the  western  flank  of  the  peak,  separated 
from  the  Sandy  by  a  high  wall,  a  somewhat  broken,  irregular  ridge  of 
trachytic,  which  extends  along  the  southwest  slope  of  the  mountain. 

"  The  upper  portion  of  the  n^ve  of  the  glacier  is  inclined  at  quite  a 
high  angle,  and  is  considerably  fissured  by  broad,  deep  crevasses.  It  has 
cut  into  the  sides  of  the  mountain  a  deep,  narrow  gorge,  with  bare,  precip- 
itous cliffs.  The  glacier  and  the  valley  of  the  Little  Sandy  are  both 
quite  narrow. 

"  One  of  the  mobt  marked  geological  and  topographical  features  of 
Mount  Hood  and  the  vicinity  is  its  very  extensive  system  of  exitinct 
glaciers,  which  everywhere  gouged  out  immense  trough-shaped  valleys, 
cutting  down  deeply  into  the  earlier  trachytic  lava  flow  of  the  old  volcano. 
The  entire  network  of  valleys  was  connected  with  two  main  glaciers, 
that  of  Hood  river  on  the  north  and  the  Sandy  on  the  south.  The 
ancient  White  River  glacier  was  undoubtedly  very  large,  but,  as  far  as  my 
observations  have  yet  extended,  had  no  tributaries." 


Mount  Baker. 

Mr.  E.  T.  Colman,  of  the  English  Alpine  Club,  ascended  Mount 
Baker  in  1869.  A  popular  account  of  this  excursion  appeared  in  Harper's 
Magazine,^  in  which  snow  fields,  glaciers,  crevasses,  etc.,  are  described  in 

1  Vol.  39,  1869,  p.  793. 


70 


GLACIERS   OF   NOllTH   AMEUICA. 


■  i  t 


such  a  manner  as  to  indicate  that  glaciers  of  very  considerable  magnitude 
are  now  flowing  down  the  mountain.  The  peak  has  since  been  ascended 
by  several  parties.  The  accompanying  illustratior  of  the  summit  of  the 
mountain  is  from  a  pliotograph  taken  by  Professor  E.  S.  Ingraham,  of 
Seattle,  Washington,  and  sliows  that  glaciers  of  conspicuous  size  may 
originate  in  unsheltered  situations. 

Glaciers  on  other  Peaks  of  the  Northwest. 

Mr.  J.  S.  Diller,  of  the  United  States  Geological  Survey,  has  made 
various  reconnaissances  and  surveys  from  Mount  Shasta  northward  to  the 
Canadian  boujidary,  and  has  observed  glaciers  of  considerable  magnitude 
on  Mount  Jefferson,  Diamond  Peak,  the  Three  Sisters,  and  Mount  St. 
Helens.  Mount  Scott  and  Mount  Thielsen  were  found  to  be  free  from 
glacial  ice.  The  group  of  peaks  known  as  the  Three  Sisters  is  considered 
by  Mr.  Diller  as  probably  affording  the  most  interesting  field  for  glacial 
studies  in  the  United  States,  with  the  exception  of  Alaska.  The  glaciers 
amid  this  group  of  peaks  attracted  the  attention  of  Dr.  J.  S.  Newberry, 
while  connected  with  the  Pacific  railroad  surveys  in  1855,  but  no  report 
of  his  observations  has  been  published. 

When  the  lofty  summits  of  the  Cascade  mountains  are  more  thoroughly 
explored,  it  will  undoubtedly  be  found  that  many  more  are  glacier-crowned 
than  have  been  reported  up  to  the  present  time.  The  glaciers  of  the 
Cascade  region  are  all  of  the  alpine  type,  but  are  somewhat  peculiar  for 
the  reason  that  they  radiate  from  isolated  peaks  which  rise  far  above  the 
nuigliboring  mountains.  These  peaks  are  all  of  volcanic  origin,  and 
lingering  manifestations  of  internal  heat  are  to  be  seen  in  the  hot  springs 
and  fumaroles  in  their  craters.  Far  down  their  flanks,  and  in  some 
instances  for  miles  out  on  the  surrounding  plains,  there  are  moraines  and 
other  evidences  showing  that  in  Pleistocene  times  the  climatic  changes, 
which  caused  half  of  the  continent  to  be  mantled  in  ice,  were  there  in 
operation  ^Jso,  and  gave  origin  to  glaciers  of  the  same  general  character 
as  those  still  existing,  but  of  far  greater  extenf,. 


i 

liij 


CHAPTER  V. 


GLACIERS    OF    CANADA. 


The  CordillerrvS  pass  northward  from  the  United  States  and  traverse 
the  western  part  of  Canada,  Ae  already  stated,  the  general  mountain 
system  subdivides  northward  and  is  composed  of  several  series  that  are 
distinct  and  separate  both  topographically  and  geologically.  The  northern 
part  of  the  system  is  far  f:i*om  being  completely  explored,  but  many 
rugged  peaks  are  known  to  reach  the  limit  of  perennial  snow,  and  to  be 
covered  in  part  with  glaciers.  About  the  only  mountaineering  that  has 
l)een  done  in  Canada  has  btien  in  the  Selkirk  and  neighboring  ranges, 
recently  made  accessible  by  the  building  of  the  Canadian  Pacific  railroad. 
When  explorers  have  conquered  other  mountains,  there  is  reason  to 
believe  from  the  reports  of  hunters,  prospectoi-s,  and  others,  that  our 
knowledge  of  the  ice  fields  will  be  greatly  extended,  and  that  many  fine 
exarai)les  of  glaciers,  of  the  alpine  type,  will  be  found  clustering  around 
the  higher  summits. 

'Jlie  glac'ers  of  the  Selkirk  mountains  are  known  principally  from 
explorations  made  by  Rev.  W.  S.  Green,  in  1888.  At  least  one 
example,  the  Illece^lewaet  glacier,  is  in  sight  from  Glacier  house  on  the 
Canadian  Pacific  railroad,  and  has  attracted  the  attention  of  thousands  of 
travelers  from  car  windows.  Views  of  this  easily  accessible  glacier  are 
given  on  Pis.  11,  12.  The  scenery  of  the  Selkirks,  as  seen  from  near  the 
summit  of  a  rugged  peak  called  Mount  Sir  Donald,  near  Glacier  house, 
is  described  by  Green  as  follows  :  ^ 

"We  were  on  a  pinnacle  of  rock,  according  to  the  barometer,  just 
10,000  feet  above  the  sea.  On  all  sides  were  vast  precipices,  and  down 
these  precipices  our  eyes  ranged  to  the  green,  forest-clad  valley  of  Beaver 
creek,  the  river  being  visible  for  many  miles,  winding,  with  an  infinity 
of  curves,  6000  feet  below  us. 

•  "  Beyond  the  river  rose  a  range  of  hills  v;ith  flattish  plateaus  on  the 
top,  flecked  with  snow.  Still  farther  to  the  e;istward,  range  rose  upon 
range,  fading  into  purple  and  blue.  Above  them  all  the  Rockies,  bearing 
silvery  white  glaciers,  formed  a  sharply  defined  sky  line,  arid  were  visible 

1  "Among  the  Selkirk  Glaciers"  (Macmillan  &  Co.,  London,  1890),  pp.  86,  87. 


72 


GLACIEliS   OF    NORTH    AMEKICA. 


for  over  ir)0  miles.  This  wonderful  panorama  constituted  our  view  to 
the  eastward.  To  the  southward  it  was  totally  different ;  in  that  direc- 
tion the  undulating  iields  of  glaciers  lay  like  a  great  soft  white  blanket 
covering  up  everything  for  ten  miles,  beyond  which  other  snow-seamed 
crags  rose,  rivaling,  probably  in  some  cases  surpassing,  Sir  Donald  in 
elevation.  To  tlie  westward  other  ranges  were  to  be  seen,  and  one  higli 
ridge  of  black  precipices  capped  by  ice  rose  high  .  »ove  the  'glacier  and 
seemed  to  dominate  the  scene.  .  .  .  Beyond  the  valley  v,f  the  lUccellewati 
to  the  northwest,  some  fine  peaks  were  visible  ;  one  dark,  bare  rock 
pinnacle  bearing  n  u-thwest  was  most  striking,  and,  no  doubt,  over  10,0nf» 
feet  high.  Our  view  to  the  northward  was  blocked  by  the  last  great 
crags  of  Sir  Donald,  from  which  we  were  cut  off  by  a  notch  200  feet 
deep.  At  its  bottom  a  narrow  rock  arete  joined  the  precipice  below  us 
with  the  face  of  the  final  peak.  Below  this  arite,  on  one  side,  lay  the 
glacier  visible  from  Glacier  house  (the  Illecellewaet  glacier) ;  and  on  the 
eastern  side,  in  a  deep  hollow,  a  fine  glacier  which  we  named  the  Sir 
Donald  glacier  commences  its  course,  and  flows  outward  in  beautii'id 
fan-like  structure,  in  the  direction  of  Beaver  creek." 

During  the  explorations  carried  on  by  Greene,  the  Illocellewact 
glacier  was  traversed  to  near  its  source,  and  several  secondary  glaciers 
discovered.  A  sketch  map  of  500  scjuar-}  miles,  embracing  many 
rugged  peaks  and  a  score  of  small  neve  fields  and  glaciers,  was  coi:- 
structed,  and  many  photographs  taken.  AVith  this  excellent  beginniii"' 
it  is  hoped  that  others  as  well  qualified  for  mountaineering  as  the  dis- 
tinguished writer  just  quoted  Avill  seek  for  new  wonders  among  the  mag- 
nificent mountains  of  Canada. 

The  present  writer  visited  the  Illecellewaet  glacier  in  the  spring  (if 
1891,  and  saw  something  of  the  wonders  of  the  Selkirks.  My  visit. 
although  brief,  served  to  confirm  the  enthusiastic  descriptions  of  that 
remarkable  region  given  by  many  travelers.  The  glaciers  about  tlie 
higher  peaks,  descending,  in  some  instances,  into  the  deep -green 
coniferous  forests,  and  producing  striking  contrasts  of  color,  are  of  the 
same  general  character  as  the  glaciei-s  of  the  High  Sierra  and  the  Cascade 
mountains.  The  extent  of  true  glacial  ice  is  greater  than  is  presented 
by  the  ice  bodies  of  California,  and  the  shining  snow  fields  from  which 
it  flows  are  broader  than  the  similar  areas  on  the  mountains  of  Oregon 
and  Washington.  In  comparison  with  the  glaciers  of  Ce'  oral  Europe. 
the  Selkirk  glaciere  lack  the  strongly  defined,  stream-like  character  of  the 
Mer  de  Glace,  or  the  Gorner  glacier,  for  example,  and,  in  general,  do  not 


i:.    .-    ... 


mm 


f;LA(IKRS  OK   NdKTII    AMEKKa 


1'I.ATK   10 


Fig.   a.  — ILLECELLEWAET   GLACIER,   CANADA. 
(Pliotograph  by  Win.  Kotinaii  &  Son.) 


Fig.   B.  — ILLECELLEWAET  GLACIER,   CANADA. 
(Photograph  by  Win.  Notraan  &  Son.) 


w 


of 


Co 
tlu 
tlu 
lie 
in 


OLA(;iEKS   OF   CANADA. 


78 


display  the  distinctive  features  of  alpine  glaciers  so  well  as  the  archetypes 
of  that  class  of  ice  bodies. 

Cilaciera  occur  farther  north  in  Canada  on  the  various  divisions  of  tlie 
Cordilleras,  more  especially  in  the  region  drained  by  the  Stikine,  and  to 
the  northeast  of  Mount  St.  Elias  ;  but  these  are  so  closely  associated  with 
the  vast  ice  bodies  of  Alaska,  that  in  the  present  sketch  political  bounda- 
ries will  l)e  ignored  and  all  of  the  glaciers  of  the  far  Northwest  included 
in  a  single  chapter. 


CHAPTER   VI. 


GLACIERS  OF  ALASKA. 


In  purchasing  Alaska  the  United  States  not  only  acquired  a  vast 
territory  rich  ii\  natural  resources,  but  added  new  wondei's  to  her  already 
varied  scenery.  As  sliown  on  the  preceding  pages,  the  glaciers  of  the 
United  States,  previous  to  the  purcluuse  of  Alaska,  were  by  no  means 
insignificant,  although  at  that  time  almost  unheard  of,  and  even  now  but 
imperfectly  explored.  When  we  include  Alaska  and  the  adjacent  portion 
of  Canada,  the  field  for  glacial  study  becomes  almost  unlimited. 

The  glaciers  of  the  Alaskan  region  are  of  the  alpine  and  piedmont 
types.  Masses  of  buried  ice  and  frozen  subsoil  in  the  tundra  region 
bordering  Bering  sea  and  tha  Arctic  ocean  and  along  arms  of  the  great 
rivers  are  not  here  included,  and  will  be  described  in  advance.  All  of 
the  true  glaciers  are  confined  to  the  southern  portion  of  the  territory  and 
depend  on  favorable  combinations  of  climatic  and  topographical  conditions 
for  their  extent  and  geographical  distribution.  The  mountains  of  the 
Alaskan  region  occur  mostly  along  its  southern  border,  adjacent  to  the 
Pacific  ocean,  and  attain  their  greatest  elevation  near  the  141st  meridian. 
The  culminating  peak,  so  far  as  at  present  known,  is  Mount  Logan, 
19,500  feet  high.  Second  in  rank  stands  Mount  St.  Elias,  18,023  feet  in 
elevation.  These  and  a  host  of  sister  peaks  rise  from  a  vast  n6v6  region 
having  a  general  elevation  of  8000  or  9000  feet.  The  entire  Pacific 
border  of  Alaska  is  rugged  and  mountainous,  and  presents  some  of  the 
most  sublime  coast  scenery  to  be  found  in  the  world.  The  currents  of 
the  ocean  bring  warm  water  to  the  very  base  of  these  lofty  mountains, 
thus  furnishing  an  evaporating  surface  in  close  proximity  to  cold  peaks 
where  the  vapors  are  condensed.  About  Mount  St.  Elias,  as  shown  by 
two  seasons  spent  by  the  writer  in  exploring  that  regioii,  the  winds  from 
the  south  are  warm  and  moist,  and  are  almost  invariably  accompanied  by 
clouds  and  snowstorms  on  the  mountains.  The  north  winds  are  dry,  and 
are  especially  welcome,  as  they  are  frequently  accompanied  by  clear  skies 
i*nd  brilliant  sunshine.  The  conditions,  taken  all  together,  are  remarkably 
favorable  for  the  growth  of  glaciers. 


w 


GLACIERS   OF    ALASKA. 


76 


NarrntlvoH  of  Enrly  Voyaifors. —  The  early  voyagers  to  the  southern 
shore  of  Ahiska  «aw  luiiny  bodies  of  ice,  some  of  which  we  now  know  are 
extensive  gliieiera.  Sir  Kdwanl  HeUfher,  in  his  account  of  the  voyage  of 
the  Sitlpliur,  niiikes  Irief  mention  of  cliffs  of  ice  on  the  borders  of  Icy 
hiiy,  near  the  the  foot  of  Mount  St.  Klia.-t. 

In  the  account  of  Vancouver's  voyages,  Iwdies  of  ice,  terminating  in 
clilTs  at  the  water's  edge,  are  mentioned  as  being  numerous  on  the  borders 
of  Prince  \,  illiam  sound.  In  the  same  narrative  brief  dcscri[)tions  are 
jfivcn  of  an  accunudation  of  ice  in  an  arm  of  Stephen's  passage,  northwest 
of  Sitka,  and  ahio  among  the  mountains  along  the  coast  opitosite  Admi- 
ralty island.  Two  large  bays  opening  north  and  west  from  I'oiat 
Couverdeen  are  described  as  terminating  in  solid  mountains  of  ice  rising 
perpendicularly  from  the  water's  edge.  Beyond  the  brief  statement  of 
the  presence  of  large  masses  of  ice  at  sea  level,  the  narratives  of  the  bold 
ex[)lorei'8  who  first  sailed  along  the  wild  Alaskan  coast  are  of  little  interest 
to  the  special  student  of  glacial  ])henomena.  ;   . 

Some  of  the  glaciers  along  the  northern  bank  of  Stikine  river  were 
visited  by  Professor  William  P.  lilake  ^  in  1863.  These  ice  bodies  are  of 
the  alpine  type,  and  descend  nearly  to  the  level  of  the  river.  A  popular 
account  of  the  remarkable  scenery  of  the  Stikine  riv'  r,  in  which  glaciers 
play  a  conspicuous  part,  was  given  by  W.  H.  Bell,  together  with  greatly 
exaggerated  illustrations,  in  Scribner's  Monthly  for  April,  1879. 

The  positions  of  many  glaciers  to  be  seen  from  the  decks  of  passing 
vessels  between  the  mouth  of  Stikine  river  and  Cook's  inlet,  a  distance 
of  about  1000  miles,  have  been  indicated  from  time  to  time  on  the  charts 
published  by  the  U.  S.  Coast  and  Geodetic  Survey.  Brief  accounts  of 
the  fine  glaciers  of  Glacier  bay  were  published  by  G.  W.  Lamplugh,  in 
Nature,^  in  1886,  but  did  not  serve  to  make  the  wondera  of  that  region 
generally  known.  Among  the  earlier  accounts  of  the  glaciers  of  Alaska, 
the  most  noteworthy  are  those  from  the  pen  of  Dr.  W.  H.  Dall,  the 
pioneer  explorer  of  the  Yukon  river  and  the  author  of  a  justly  celebrated 
work  on  "  Alaska  and  its  Resources." 

This  brief  account  of  the  sources  of  information  relating  to  the 
glaciers  of  the  Alaskan  region  available  in  3  883,  when  the  author's  sketch 
of  the  "  Glaciers  of  the  United  States  "  was  written,  brings  us  to  the  time 

'  Blake's  observations  were  the  earliest  made  in  southeastern  Alaska  that  have  much 
scientific  value,  and  were  recorded  in  the  American  Journal  of  Science,  vol.  44,  1867,  pp. 
W-101.  Republished  with  a  map,  in  a  report  to  the  Secretary  of  State,  bearing  the  title^ 
"Geographical  Notes  upon  Russian  America  and  the  Stickeen  River.     Washington,  1808." 

»  Vol.  33,  pp.  299-301. 


76 


GLACIEHS   OF   NORTH    AMERICA. 


when  a  wide  interest  was  awakened  in  the  natural  features  of  the  "  Far 
Noi-thwest." 

'-'  Kecent  Exploj-ations.  —  Of  the  more  recent  Alaskan  eyplorei-s  we 
are  indebted  especially  to  John  Muir,  who  discovered  the  magnificent 
g'acier  since  nam(^d  in  his  honor,  as  well  as  many  othei"s  that  come  down 
to  the  sea,  or  may  be  seeu  from  a  canoe  while  threading  the  intricate 
straits  and  bays  of  the  southeastern  portion  of  the  territory.  More 
recently  the  glacierj  of  Glacier  bay  have  been  studied  by  Professor  G. 
Frederick  Wright  and  Professor  H.  Fielding  Reid,  and  the  still  vaster  ice 
streams  in  the  regions  about  Mount  St.  Elias  and  Disenchantment  bay 
have  been  visited  and  described  by  a  number  of  persons.  Reference  to 
the  principal  contributions  to  the  literature  that  iias  grown  out  of  these 
explorations  are  given  in  the  following  footnote.^ 

Some  of  the  glaciers  flowing  northward  from  the  mountains  of 
southern  Alaska  were  examined  and  their  positions  mapped  by  Dr.  C. 
Willard  Hayes,  of  the  U.  S.  Geological  Survey,  during  a  bold  and  highly 
successful  exploration  from  the  Yukon  to  Copper  river,  in  company  with 
Lieutenant  Frederick  Sclnvatka,  in  1891.2  Other  northward-flowing 
glaciers  were  observed  by  E.  J.  Glave  in  1891  ind  1892,  to  the  north- 
west of  the  head  of  Lynn  canal. 

In  addition  to  the  writings  of  the  travelers  referred  to  above,  much 

,     1  John  Muir,  "  Ahaska,"  in  Am.  Geol.,  vcl.  11,  1893,  pp.  287-299. 
■        't.  F.  Wright,  ''The  Ice  Age  in  North  America,"  Appleton  &  Co.,  1889. 

11.  Fielding   Reid,  "Studies   of   Muir  Glacier,"  in  National   Geographic  Magazine 
(Washington,  D.C.),  vol.  4,  1892,  pp.  19-84. 

Frederick  Schwatka,  "  The  Expedition  of  tht  New  York  Times,"  in  Ceniury  Magazine, 
April,  1891. 

William  Libbey,  Jr.,  "Some  of  the  Geographic  Features  of  3outheastern  Alaska,"  in 
Am.  Geog.  Soc,  Bull,,  1880,  pp.  279-300. 

H.  W.  Seton-Kair,  "  Shores  and  Alps  of  Al'.ska,"  London,  1887. 

H.W.  Seton-Karr,  "Alpine  Regions  of  Alaska,"  in  Roy.  Geog.  Soc,  Free.  (London), 
vol.  9,  pp.  2(59-285. 

William  Williams,  "  Climbing  Mount  St.  Eiias,"  in  Scribner's  Magazine,  vol.  5i  1889, 
pp.  387-403. 

11.  W.  Topliam,  "An  Expedition  to  Mount  St.  Elias,"  in  the  Alpine  Journal  (London), 
vol.  14,  1889,  pp.  345-371. 

I.  C.  Russell,  "An  Expeditioii  to  Mount  St.  Elias"  (1890),  in  National  Geographic 
Magazine  (Washington,  D.C),  vol.  3,  1891,  pp.  53-203. 

I.  C.  Russell,  "Second  Expedition  to  Mount  St.  Elias,"  1391,  in  13th  Ann.  Rep.  U.  S. 
Geol.  Snrv.,  pp.  1-91. 

John  Muir,  Century  Magazine,  vol.  60,  1896,  pp.  234-247 

«"An  Expedition  to  tlie  Yukon  District,"  in  National  Geographic  Magazine  (W^asli- 
ington,  D.C),  vol.  4,  1892,  pp.  117-162. 


1  ■; 


GLACIERS    OF    AT,ASKA. 


77 


])opul..r  interest  in  the  subject  here  treated  has  lieen  awakened  by  the 
enthusiastic  narratives  of  tourists  who  hav<^  made  trips  on  the  excursion 
steamers  sailing  from  Puget  sound  through  the  celebrated  "  inland 
passage  "  to  Taku  inlet,  Lynn  canal,  Glacier  bay,  etc. 

From  this  brief  summary  it  will  be  seen  that  the  literature  relating 
to  the  glaciers  of  the  Alaskan  region  is  already  voluminous.  Instead  of 
attempting  to  give  a  detailed  account  of  all  the  glaciers  that  have  l)een 
described,  a  few  of  the  best-known  examples  will  be  selected  as  types. 
These  may  be  taken  as  representatives  of  the  many  hundred  already 
known,  and  as  indicating  the  principal  features  of  the  probably  still 
greater  number  that  have  only  been  seen  from,  a  distance  or  remain  to  be 
discovered. 

TiLF.- WATER  Glaciers. 

It  is  convenient  to  give  a  special  name  to  glaciers  which  enter  the 
ocean  and  break  off  so  as  to  form  bergs.  One  should  bear  in  mind,  how- 
ever, that  the  ice  sti  3ams  or  ice  sheets  which  terminate  in  this  manner  do 
not  differ  from  neighboring  glaciers  that  fail  to  reach  the  sea,  except 
in  the  fact  that  they  actually  meet  tide-water.  But  the  striking  appear- 
ance of  their  broken  extremities  rising  in  sheer  precipices  above  the  surf 
that  beats  against  their  bases,  rendero  them  especially  noteworthy  and 
warrants  their  having  a  special  designation. 

The  tide-water  glaciera  of  Alaska  are  the  ones  that  claim  the  greatest 
share  of  £.dmiration  from  tourists  on  account  of  the  wonderful  colorincr 
and  marvelous  beauty  of  their  ice  cliffs  and  the  picturesqueness  of  the 
floating  islands  of  ice  ta  which  they  give  oi-igin.  The  approach  to  a  tide- 
water glacier  is  usually  first  made  known  by  the  fleet  of  bergs  that  dot 
the  water  and  chill  the  atmosphere.  Tiiese  become  more  numerous  as 
one  proceeds,  and  many  times  completely  cover  the  water  before  the  ice 
cliffs  from  which  they  came  can  be  seen.  Indeed,  at  times,  the  floating 
bergs  form  an  impenetrable  pack  through  which  it  is  impossible  for  a 
vessel  to  advance.  The  vicinity  of  a  glacier  which  terminates  in  the  sea 
is  frequently  made  manifest  also  by  the  roar  of  avalanches,  as  iresh  masses 
of  ice  fall  from  its  face  and  join  the  fleet  of  gleaming  bergs  crowding  the 
adjacent  watei-s.  The  noise  of  the  falling  fragments  may  l)e  heard  many 
miles,  and  sounds  like  distant  thunder  or  the  discharge  of  heavy  guns. 

When  a  large  tide-water  glacier  is  seen  for  the  first  time,  the  beholder 
is  fascinated  by  its  beauty,  especially  if  it  is  ilium,"  nated  by  a  brilliant 
sun,  and  learns  a  new  lesson,  for  the  reason  that  the  scene  is  so  dififei'ent 


1 

If 

1 

j 

I 

'1 

1 

1 

'1 

'f 

I 

'. 

,i 

i 

1     • 

I  ; 


J  ■ 


it 


78 


GLACIERS   OF  NORTH   AMERICA. 


from  the  popular  idea  of  the  appearance  of  glaciers,  derived  principally 
from  the  well-known  ice  streams  of  Switzerland. 

In  going  to  Alaska  by  the  customary  "  inland  passage,"  through  the 
picturesque  archipelago  fringing  the  coast  from  Puget  sound  northward, 
the  first  floating  ice  is  usually  seen  soon  after  passing  through  Wrangell 
narrows  and  emerging  into  an  arm  of  Frederick  sound.  These  bergs  come 
from  a  small  glacier  long  known  to  the  Indians  as  Hutli,  or  the  thunderer, 
on  account  of  the  noise  produced  by  ice  falling  from  its  face.^  The  glacier 
is  hidden  by  tlie  bold,  forest-covered  shores  of  Hutli  inlet,  and  is  not  seen 
by  travelers  along  the  course  ordinarily  followed  by  vessels. 

Proceeding  northward,  glimpses  are  obtained  here  and  there  on  the 
mountains  of  the  mainland,  of  gleaming  snow  fields  and  of  the  blue  of 
glacial  ice,  rising  abo"e  the  nearly  universal  green  of  the  forest-covered 
shores.  The  first  unobstructed  view  of  a  large  glacier  is  not  had,  however, 
until  one  enters  a  wild  fiord  known  as  Taku  inlet.  On  the  northwest 
shore  of  this  indentation  of  the  coast,  and  seen  on  the  left  as  one  enters 
it  from  the  sea,  a  stream  of  ice  descends  from  the  mountains  and  expands 
into  a  broad,  fan-like  terminus  at  the  margin  of  the  water.  This  is  the 
Norris  glacier  shown  on  Plate  11.  The  mud  and  sand  brought  out  by  the 
streams  issuing  from  the  ice  have  formed  a  fringe  about  its  terminus,  so 
that  it  is  now  separated  from  the  water  of  the  inlet  by  a  barren  plain  of 
sand  and  mud  crossed  by  many  bifurcating  streams. 

Taku  Glacier. 

The  comparative  mildness  of  the  scenery  at  the  Norris  glacier  does 
not  prepare  one  for  the  marvels  that  await  him  a  few  miles  beyond.  At 
the  head  of  Taku  inlet,  and  filling  the  gorge  from  side  to  side  so  as  to 
hold  the  watera  of  the  ocean  in  check,  is  a  wall  of  ice  formed  by  the 
extremity  of  a  typical  tide-water  glacier.  This  is  the  Taku  glacier,  as  it 
has  long  been  called  by  both  Indians  and  white  people.  Unfortunately 
an  attempt  has  recently  been  made  by  the  U.  S.  Coast  and  Geodotic 
Survey^  to  supplant  this  name  by  another  less  appropriate. 

1  This  glacier  v.  as  first  seen  by  John  Muir,  and  the  Indian  name  which  he  accepted 
should  be  recognized.     See  American  Geologist,  vol.  2,  p.  291. 

8  The  Hutli  and  Norris  glaciers  referred  to  above,  a«  well  as  several  others  in  south- 
eaf.tem  Alaska,  have  also  suffered  a  recent  change  of  name  on  the  charts  of  the  U.  S.  Coast 
and  Geodetic  Survey.  I  wish  to  protest  against  this  useless  duplication,  especially  when  the 
names  of  persons  temporarily  in  political  power,  and  for  this  reason  simply,  are  put  in  place 
of  names  long  in  use,  and  especially  of  pronounceable  Indian  namet'. 


lately 
jdotic 

1       ^ 

- 

3cepted 

1        S 

south- 

1  ■"■' 

.  Coast 

B 

hen  the 

H 

n  place 

■     ' 

'  li 


and 
'  full 
stru 
esti: 
she( 

sun 

The 

the 

houi 

espe 

flow 

can 

regii 

uren 


as   t 

expo 

nnilt 

and  ( 

deepi 

marii 

outei 

becoi 

ice  el 

it  is 

obser 

be  fori 

reven 

falls  i 

The  V 

pice, 

the  ei 

waves 

I'ockin 

fl'Cqut 

carrie( 

Gas  til] 


GLACIEUS    OF   ALASKA. 


79 


Taku  glacier  heads  far  bad:  in  the  mountains,  no  one  knows  where, 
and  flows  toward  the  coast  as  a  well-defined  ice  stream.  It  is  yet  in  its 
full  strength  when  it  reaches  an  arm  of  the  sea  and  enters  on  an  unequal 
struggle  with  the  waves.  The  wall  of  ice  rising  above  the  water  is  by 
estimate  200  feet  high,  and  nearly  a  mile  in  length.  Its  face  is  not  one 
sheer  precipice,  but  is  broken  into  buttresses  and  columns  and  diversified 
by  alcoves  and  recesses.  Its  crest  line  is  irregular  and  serrate,  and 
surmounted  by  spires  and  battlements  of  the  most  varied  description. 
The  details  of  the  craggy  slope  are  constantly  changing  and  are  never 
the  same  for  two  successive  days.  In  fact,  marked  changes  occur  from 
hour  to  hour  as  fresh  masses  fall  into  the  sea.  The  rapid  waste,  manifest 
especially  on  summer  days,  is  counterbalanced  by  the  resistless  onward 
flow  of  the  ice,  so  that  but  slight  changes  in  the  position  of  the  terminus 
can  be  recognized  from  year  to  year.  Like  many  glaciers  in  the  same 
region  its  extremity  is  probably  slowl)'-  retreating,  however,  but  no  meas- 
urements have  been  made  to  show  the  rate  of  recession. 

The  color  of  the  fractured  and  cleft  ice  cliffs  is  as  varied  and  beautiful 
as  their  ever-changing  forms.  The  surfaces  that  have  been  longest 
exposed  to  the  atmosphere  are  white  and  glittering,  on  account  of  the 
multitude  of  vesicles  formed  in  the  partially  melted  ice  ;  but  the  clefts 
and  caverns  reveal  the  intense  blue  of  the  crystal  mass  within.  In  the 
deeper  recesses  the  light  issuing  from  the  interior  is  of  the  darkest  ultra- 
marine, so  deep  that  it  appears  almost  black  in  contrast  with  the  brilliant 
outer  surface.  In  the  full  glory  of  an  unclouded  summer  day  the  scene 
becomes  resplendent  with  the  reflected  glories  of  the  sea  and  sky.  The 
ice  cliffs  blaze  and  flash  in  the  sunlight  until  one  can  scarcely  believe  that 
it  is  an  everyday,  earthly  scene  that  meets  his  admiring  gaze.  The 
observer  to  whom  such  wonders  are  novel  may  well  fancy  that  the  picture 
before  him  is  but  the  fantasy  of  a  dream.  One  is  awakened  from  such 
reverie,  however,  by  a  crash  like  the  roar  of  artillery,  when  an  avalanche 
falls  from  the  cliffs  of  light  and  is  engulfed  in  the  turbid  waters  below. 
The  white  foam  shot  upwards  by  the  avalanche,  rises  high  on  the  iry  preci- 
pice, and  perhaps  dislodges  other  tottering  pinnacles,  which  reawaken 
the  echoes  in  the  neighboring  mountains.  After  each  crash,  crested 
waves,  starting  away  from  the  scene  of  commotion,  set  numerous  bergs 
locking,  and  break  in  lines  of  foam  on  the  adjacent  shore,  xloating  ice 
frequently  whitens  the  entire  surface  of  Taku  inlet,  and  is  occasionally 
carried  by  the  wayward  currents  far  out  into  Stevens'  passage  and  up 
Ciastineau  channel  to  beyond  the  town  of  Juneau. 


l5; 


80 


GLACIERS   OF   NORTH   AMERICA. 


In  former  years  Taku  glacier  extended  far  south  of  its  present 
terminus  and  received  Norris  glacier  as  a  tributary.  The  former  height 
of  the  ice  is  clearly  marked  by  the  smoothed  and  rounded  surfaces  of  the 
cliffs,  and  by  grooves  and  striations,  for  about  2000  feet  above  the  water, 
on  the  precipitous  mountains  enclosing  the  inlet.  Above  that  height  the 
rough  and  angular  sculpturing  due  to  frost,  rain,  and  rills  is  in  marked 
contrast  to  the  ice-worn  surfaces  below.  The  glacier  is  still  receding, 
and  in  a  decade  or  two  will  probubly  have  shrunken  so  that  it  will  no 
longer  reach  the  inlet,  but  will  end  as  Norris  glacier  now  does,  with  a  low 
frontal  slope.  The  waters  from  the  glacier  will  then  build  an  alluvial 
plain  about  its  extremity,  and  it  will  acquire  the  subdued  and  unpic- 
turesque  features  characteristic  of  dying  alpine  glaciers. 


MuiR  Glacier. 

.  •        (A  map  of  Muir  glacier  is  given  on  Plate  12.) 

Proceeding  westward  from  Taku  inlet,  the  next  tide-water  glacier  is 
met  with  in  Glacier  bay.  Several  glaciers  there  pour  their  icy  floods  into 
a  land-locked  arm  of  the  sea.  The  wonders  of  this  splendid  bay,  now 
familiar  to  thousands  of  tourists,  were  unknown  to  civilized  people 
fifteen  years  ago.  The  bay  and  the  magnificent  glacier  on  its  shores  were 
discovered  by  John  Muir,  the  intrepid  mountain  climber  and  poetic  writer 
of  California,  in  1878.  His  account  of  the  pioneer  trip  to  Sita-da-ka^  as 
the  bay  was  called  by  his  Indian  comi)anions,  has  recently  been  i^ul)- 
lished,  and  is  a  most  graphic  and  interesting  account  of  a  canoe  trip 
among  the  islands  of  southeastern  Alaska.^ 

One  of  the  largest  and  at  present  the  best-known  glacier  enterini,^ 
Glacier  bay  has  been  named  Muir  glacier,  in  honor  of  its  discoverer.  In 
1886,  Prof.  G.  Frederick  Wright,  with  three  companions,  encamped  for 
about  a  month  ne.ar  the  eastern  end  of  the  ice  cliffs  in  which  it  termi- 
nates, and  began  the  study  of  its  general  features,  its  motions,  the  forma- 
tion of  icebergs,  etc.^ 

The    observations    begun    by   Wright   were   continued   and   greatly 

1  This  brief  account  of  explorations  in  southeastern  Alaaka  was  first  published  as  a 
"  folder"  by  the  Northern  Pacific  Railroad  Co.  and  afterward  printed  in  the  American  Genl- 
ogist,  vol.  11,  1893,  pp.  287-209.  A  revision  of  this  charming  paper,  accompanied  by  fine 
illustrations,  appeared  in  Century  Magazine,  vol.  50,  1896,  pp.  234-247. 

*  The  principal  account  of  these  observations  may  be  found  in  "Wright's  book,  "  The  Ice 
Age  in  North  America,"  Appleton  &  Co.,  1889. 


i    1 


Glaciers  of  North  ^iMERiCA. 


Plate  13. 


I 


m 


GLACIEUS    OF    ALASKA. 


81 


extended  by  Trof.  H.  Fielding  Keid,  and  a  nnnil)er  of  as!!«i8tants,  in  1890,' 
and  again  in  18'J'2. 

The  i>iesent  writer  visited  Mnir  glaeier  in  1800,  as  a  passenger  on  the 
excursion  steamer  Queen,  and  spent  a  few  hours  in  viewing  the  general 
features  of  the  region.  Nearly  all  of  the  facts  presented  below  in  reference 
to  the  more  detailed  cliaracteristics  of  the  glacier,  however,  are  taken 
tiom  the  reports  of  Professoi-s  Wright  and  Keid. 

On  entering  Glacier  bay  from  ley  strait,  one  sees  before  him  a  mag- 
nitii'ent  inlet,  the  head  of  which  is  beyond  the  reach  of  vision.  The  bay 
is  35  miles  long  and  from  six  to  ten  miles  broad.  To  the  west  rises  a 
group  of  8now-(!lad  and  glacier-scored  mountains,  culminating  in  Mt. 
Fiiirweather,  over  15,000  feet  high.  The  ^.e  flowing  from  the  northeast 
slope  of  this  rugged  elevation  reaches  the  western  shore  of  Glacier  bay 
and  forms  a  series  of  splendid  tide-water  glaciere.  These  were  explored 
and  mapped  by  Ileid  in  1892,  but  an  account  of  them  hiis  not  yet  been 
l)ul)lished,  although  their  names  and  positions  are  sometimes  roughly 
indicated  on  charts  of  the  bay. 

As  one  proceeds  up  the  Glacier  bay  large  fields  of  floating  ice  are 
usually  encountered  and  numerous  bergs  are  always  in  sight.  These 
floating  fragments  of  glacial  ice  are  driven  here  and  there  by  the  winds 
and  currents,  so  that  the  details  of  the  arctic  picture  are  constantly  chang- 
ing. At  times,  the  ice  is  packed  in  such  a  way  that  it  is  difficult  if  not 
inii)ossible  for  vessels  to  force  a  passage  through  it  so  ac  to  gain  the  im- 
mediate vicinity  of  the  glacier  beyond. 

The  truly  wonderful  scenery  of  Glacier  bay  appeals  most  forcibly  to 
the  imagination  during  the  lengthened  twilights  of  summer.  The 
latitude  corresponds  with  that  of  the  extreme  north  of  Scotland.  In 
summer  the  sun  declines  but  a  few  degrees  below  the  northern  horizon 
and  the  nights  are  sufficiently  light  to  reveal  the  white-robed  mountains 
in  half-tones  of  the  most  delicate  beauty.  At  such  times  the  thousands 
of  bergs  and  the  broad  ice-floes  are  transformed  by  the  tricks  of  the 
mirage  into  shapes  of  the  most  remarkable  description.  Vast  cities,  with 
colonades  and  ruined  temples,  towera  and  battlements,  appear  with  mar- 
velous realism  where  only  a  few  moments  before  there  was  but  a  glassy 
plain  of  water  studded  with  fragments  of  floating  ice.  Sheaf-like  foun- 
tains and  monumental  shafts  appear  with  such  faithful  imagery  that  one 
is  more  than  half  inclined  to  yield  to  the  delusion  and  believe  that  the 

^  A  report  on  this  survey  was  published  by  Reid  in  the  National  Geographic  Magazine, 
Vol.  4,  1802,  pp.  19-48. 


! 


! 
i 


I 


I 


82 


OLACIEK8   OP   NOUTH    AMEItlCA. 


apparitions  are  real.     The  weird  l)eauty  of  the  expanse  of  ice-freij^hted 
watei-s  and  the  cold,  stern,  snow-covered  mountains,  as  well  as  the  lively 
anticipation  of  what  is  to  come,  make  a  sail  on  those  northern  watere,  in 
brilliant  weather,  an  event  that  thrills  the  fancy  and  leaves  an  indelibh 
picture  on  the  memory. 

On  nearing  the  head  of  Glacier  bay  and  approaching  Mnir  inlet,  one 
beholds  a  palisade  of  ice  nearly  two  miles  long  and  from  130  to  210  feet 
high,  rising  from  the  water  and  uniting  mountain  with  mountain  and 
forming  a  wall  across  the  head  of  the  inlet  so  as  to  hold  back  the  waters 
of  the  ocean.  This  wall  of  ice,  shown  on  Plate  3,  is  the  extremity  of  the 
justly  famed  Muir  glacier.  As  one  draws  near,  the  surface  of  the  glacier 
can  be  seen  above  and  beyond  the  line  of  precipices  in  which  it  termi- 
nates. The  eye  follows  the  gradually  ascending  plain  of  white  to  the 
distant  mountains,  where  it  divides  into  many  branches,  separated  by 
wild,  rugged  peaks  that  stand  as  islands  in  the  vast  snow  field. 

Soundings  made  in  the  central  portion  of  the  inlet  as  near  to  the  ice 
front  as  vessels  can  safely  venture,  by  estimate  a  thousand  yards  from 
the  base  of  the  cliffs,  gave  a  depth  of  720  feet.  The  glacier  extendotl 
south  of  its  present  limit  a  few  years  since  and  occupied  the  site  when; 
this  sounding  was  taken,  and  was  then  certainly  fully  one  thousand  feet 
thick.  There  are  reasons  for  believing  that  recent  changes  have  not 
sensibly  altered  the  depth  of  the  ice. 

Surveys  made  by  Reid  have  shown  that  the  onward  flow  of  the  ice 
near  the  end  of  the  glacier,  in  its  central  portion,  is  seven  feet  per  day, 
and  decreases  to  zero  at  the  sides. ^  Knowing  the  width  and  thickness  of 
the  ice  and  its  iate  of  flow,  it  has  been  computed  that  about  thirty  million 
cubic  feet  of  ice  break  away  each  summer  day  and  join  the  fleet  of  berths 
that  whiten  the  adjacent  watera.  The  flow  of  the  ice  in  winter  is  less 
than  in  summer,  but  no  winter  measurements  have  been  made.  Judgiiiti- 
from  the  behavior  of  other  glaciers,  it  seems  safe  to  assume  that  tlie 
annual  onward  flow  where  the  current  is  strongest  is  not  less  than  2000 
feet. 

The  color  of  the  ice  wall  in  which  the  Muir  glacier  terminates  is  nf 
the  same  marvelous  character  as  already  noted  at  Taku  glacier.  It  is 
especially  remarkable  for  the  deep  ultramarine  of  the  recesses.  The 
multitude  of  pinnacles  and  spires  forming  the  serrate  crest,  as  well  as 
each  outstanding  buttress  of  the  mighty  wall,  are  brilliant  white.     Tlie 

1 S.  Prentiss  Baldwin,  "  Recent  Changes  in  Muir  Glacier,"  in  American  Geologist,  vol, 
11,  pp.  307-375. 


GLACIEKS    OF    ALASKA. 


88 


contrast  in  color  and  in  form  are  greatest  and  most  l)eantifnl  when  the 
side  lights  of  morning  and  evening  hring  out  the  details  in  strong  relief, 
i'lie  crumbling  cliffs  are  a  ruin  that  is  constantly  renewed.  The  resist- 
ance offered  by  individual  features  to  the  sun  and  air  is  brief,  but  new 
forms  take  the  place  of  tin  se  that  succumb,  and  the  general  effect  remains 
tiie  same.  One  never  wearies  of  watching  the  ever-changing  picture  pre- 
sented by  the  long  line  of  cliffs  in  varying  lights,  or  of  studying  the 
formation  of  bergs  as  buttress  after  buttress  gives  way  to  the  attacks  of 
the  waves  and  topples  over  into  the  sea. 

Icebergs.  —  The  avalanches  from  the  faces  of  tide-water  glaciei-s  take 
place  without  warning  and  are  fre(piently  startling.  The  roar  of  the 
falling   masses   on    hot  summer  days    is   sometimes   almost   continuous. 


II 


Fi<i.  5.  —  IcEBEHo,  MuiR  Inlet,  Alaska. 

]\Iuir  states  that  in  the  case  of  the  glacier  named  in  his  honor,  for  twelve 
consecutive  hours  the  number  of  discharges  loud  enough  to  be  heard  a 
mile  or  two  were,  by  actual  count,  one  in  five  or  six  minutes.  The  dis- 
lodged masses  falling  into  the  sea  cause  great  disturbances,  and  send  the 
white  foam  surging  high  up  on  the  cliffs.  On  one  occasion,  while 
traversing  the  surface  of  Muir  glacier  near  its  extremity,  my  attention 
was  attracted  to  a  pinnacle  higher  than  its  neighbors,  on  the  brink  of  the 
precipice  overlooking  the  water.  While  I  was  still  gazing,  it  suddenly 
disappeared  from  sight,  and  after  a  few  seconds  a  cloud  of  spray  rose  in 
its  place.  This  is  the  only  instance  I  recall  in  which  the  spray  dashed 
upward  by  falling  ice  rose  higher  than  the  general  level  of  the  crest  of 
the  precipice  from  Avhich  it  was  detached. 


84 


OLACIKU8    OK    NOKTII    AMKIIK.'A. 


The  icelKT^s  of  Gliu-ier  ])ay  an<l  otluT  portions  (»f  tlic  Alaskiin  coast 
are  Hinall  in  (!ompari.son  with  those  of  the  (iieenhnul  waters.  Actual 
measurements  are  not  at  hand  ;  but  after  several  canoe  trips  amon<(  the 
rtoatin^  ice,  I  sliouM  jud^'tj  that  llie  hir^cr  herd's  are  freqiu'utly  loO  to 
200  feet,  Umg  by  fiO  to  100  feet  broad,  ami  rise  20  to  30  feet  alx)ve  the 
water.  As  they  float  with  aliout  one-seventh  of  their  mass  exposed,  tlieir 
total  depth  can  be  readily  estimated. 

In  sailing  >ip  Muir  inlet  or  any  other  arm  of  the  sea  on  the  wild 
Alaskan  shore  whcni  tide-water  {glaciers  disdiarge,  one  notices  that  tlif 
bcr^s  vary  in  character,  but  may  be  grou])ed  in  three  cjuite  well-dclincd 
classes.  Some  are  of  dazzling  whiteness  ;  others  are  of  the  color  of  tur- 
(juoise  or  beryl  ;  others,  again,  are  dark  with  dirt  and  stones.  On  watch- 
ing the  ice  cliffs  where  these  children  of  the  gl{iciei*s  are  l)orn,  we  find  that 
when  pinnacles  already  whitened  by  ex[)osure  to  the  air  fall  into  the  sea. 
they  float  away  as  white  bergs.  If  we  watch  them  drifting  over  the  still 
water  and  a[)[)caring  in  the  distance  like  a  fleet  of  glcatning  sails,  we  note 
that  occasionally  a  white  berg  snddetdy  turns  over  with  great  commotion 
and  joins  the  fleet  having'  lilue  for  their  banner.  The  reason  for  the 
change  in  color  is  that  previous  to  turning  over  the  porous  exterior  of 
the  submerged  portion  of  the  berg  was  dissolved  away  so  as  to  expose  the 
compact  ice  of  the  interior.  The  sudden  revei'sion  of  position  is  due  to 
unequal  melting,  which  changes  the  center  of  gravity  of  the  mass.  A 
cone  of  ice  in  which  the  height  is  about  equal  to  the  diameter  of  the  base, 
will  float  with  its  apex  down.  When  a  l>erg  api)roaches  a  conical  form, 
the  position  of  greatest  stability  is  one  in  which  the  side  having  the 
larger  mass  is  uppermost.  Bergs  do  not  become  top-heavy  and  turn  over, 
as  is  sometimes  stated,  but  liecome  hottom-huoyant  and  tend  to  adjust 
themselves  to  the  medium  in  which  they  float. 

Blue  bergs  are  also  formed  by  the  breaking  away  of  portions  of  the 
submerged  ice  foot  of  tide-water  glaciers.  These  are  frequently  of  laryc 
size,  and  rise  from  below  the  surface  of  the  water  well  in  advance  of  the 
visible  end  of  the  glacier.  Their  emergence  is  sudden.  They  bound  ti> 
the  surface,  and  rising  well  above  it  carry  tons  of  water  with  them.  After 
rocking  to  and  fro  for  several  minutes  as  if  to  be  sure  of  their  freedom  after 
centuries  of  imprisonment,  they  quiet  down  and  float  slowly  away  as  shiiii- 
mering  islands  of  the  most  exquisite  blue.  The  precise  manner  in  which 
the  bottom  ice  of  a  tide-water  glacier  breaks  off  is  not  definitely  known. 
Reid  has  made  observations  in  this  connection  at  Muir  glacier,  and  has 
been  led  to  think  that  the  r^  )per  portion  of  the  submerged  ice  foot  extends 


(ll.A<  IKUJ*  i>K  Nmi  I II   Ami  iti.  \. 


I'laTR  U. 


Fig.   a.       ice    CLIFF   AT    THE    END    OF    MUIR    GLACIER,   ALASKA. 

(Photoijraph  by  11.  F.  Uei<l.) 


q^HH^H^^^^^^^H^P^ir^^ 

l^^H^H^I 

^H^^^H^^H 

«SbhIh^^^^^^^^I 

^^^^H 

IQ^^P 

Fig.    B.  — ICE    CLIFF   OF    MUIR    GLACIER    AT    LOW    TIDE. 

(PlioiiiaiiiOii  bi  I!,  f".  Kfiil.) 


GLACIERS   OF   ALASKA. 


85 


beyond  and  overhangs  the  lower  portion,  for  the  reason  that  the  flow  of  a 
glacier  is  greater  at  the  top  than  at  the  bottom,  and  also  because  the  melt- 
ing of  the  submei'ged  ice,  at  least  near  the  surface  of  the  sea,  is  in  excess 
of  the  melting  of  the  portion  above  water.  These  considerations  have  led 
to  the  assumption  that  a  longitudinal  section  of  the  extremity  of  a  glacier 
terminating  in  deep  water  would  present  the  features  indicated  in  the 
following  diagram : 


Fl&.  6.  —  IDKAL  SKCTION  OP  THE  END  OF  A  TiDE-WATEB  GLACIER.     AFTER  REID. 

The  broken  lines  extending  down  from  the  surface  and  curving  outward 
are  thought  to  represent  the  direction  taken  by  fractures,  v/hich  permit 
portions  of  the  extremity  to  break  off  and  leave  an  overhanging  mass  near 
the  summit  of  the  cliff.  The  submerged  portion  would  then  breaF  away, 
and  owing  to  its  irregular  form,  might  be  thrown  oittward  as  it  rose,  so 
as  to  come  to  the  surface  some  distance  from  the  visible  base  of  the 
ice  cliff. 

The  principal  objection  to  this  explanation,  so  far  as  can  be  judged 
from  the  observations  available,  is  that  the  bergs  rising  from  below  reach 
*\e  surface  too  far  out  from  the  ice  cliffs.  In  some  instances  observed  by 
tiie  present  writer,  they  came  to  the  surface  not  less  than  a  thousand  feet 
from  the  visible  ice  foot.  Besides,  the  observed  rapid  melting  of  the 
submerged  ice  pertains  to  the  portion  within  a  few  feet  of  tlie  surface. 
Near  Muir  glacitr  the  surface  temperature  of  the  water  of  JIuir  inlet,  as 
observed  \  y  Prof.  Wright,  was  40°  F.  This  would  insure  rapid  melting, 
but  what  the  temperature  is  below  the  surface  no  one  knows. 

Another  explanation  of  the  formation  of  bergs  from  the  submerged 
jwrtion  of  a  glacier,  is  that  the  falling  of  avalanches  from  the  visible  por- 
tion of  the  ice  cliff  is  greater  than  the  melting  of  the  submerged  ])ortion. 
A  terrace-like  projection  of  the  deeply  submerged  ice  foot  is  then  pro- 
duced, and  poj'tions  of  the  protruding  base  break  away  from  time  to  time, 
owing  to  their  buoyancy,  and  rise  to  the  surface.  The  conditions  here 
))ostulated  are  illustrated  in  the  diagram  on  the  following  page. 


86 


GLACIERS   OF    NOKTH   AMERICA. 


]{ei(l  objects  to  the  hypothesis  just  stated,  and  suggests  that  the  height 
to  which  tlie  suddenly  emerging  bergs  rise  above  tlie  surface  of  the  watei' 
is  not  so  great  as  should  be  expected  if  they  came  from  a  depth  of  several 
hundred  feet.  Until  observations  or  computations  have  shown  that  this 
objection  is  valid,  however,  it  can  have  but  little  weight.  Which  of  these 
two  explanations  is  correct,  or  what  portion  of  each  may  be  accepted  with 
confidence,  must  be  determined  by  future  observations.  It  would  not  be 
difficult,  or  especially  dangerous,  to  make  soundings  and  temperatur3  cl> 
servations  in  the  central  part  of  Muir  inlet  close  to  the  visible  base  of  thft 
ice  wall,  and  thus  ascertain  the  slope  of  the  submerged  portion  of  the 
glacier,  and  also  to  what  depth  the  warm  8urfac(5  temperature  extends. 

The  black,  dirt-covered  bergs  occasionally  seen  in  the  vicinity  of  tide- 
water glaciers  are  fragments  of  the  bottom  layei-  of  ice,  or  perhaps  more 
frequently  portions  of  the  sides  of  crevasses  in  which  stones  and  dirt  Iiad 


1 1 


Fio.  7. —Ideal  Section  of  the  End  of  a  Tide-watek  G',.a(ier. 

lodged.  These  bergs,  bearing  a  freight  of  foreign  material,  derive  their 
principal  interest  from  the  fact  that  they  carry  their  loads  to  localities 
more  or  less  remote  from  their  place  of  origin,  and  may  drop  them  where 
fine  water-borne  sediments  are  accumulating. 

An  Ancient  Forest  Buried  beneath  the  Ice.  —  When  the  excursion 
steamer  to  Glacier  bay  reaches  within  about  a  mile  of  Muir  glacier,  the 
anchor  is  dropped  and  passengers  are  given  an  opportunity  to  go  ashore. 

On  landing  on  either  side  of  the  inlet,  the  first  fact  that  attracts  the 
attention  of  the  geologist  is  the  presence  of  a  heavy  deposit  of  cross- 
stratified  sand  and  gravel  below  the  extremity  of  the  glacier.  This  gravel 
deposit  passes  beneath  the  glacier  and  is  plainly  of  more  ancient  date 
than  the  advance  of  the  ice  over  it.  In  this  deposit  there  are  many 
trunks  and  branches  of  trees ;  and  on  the  west  side  of  the  inlet  there  are 
a  score  or  more  trunks  of  spruce  trees,  still  standing  as  they  grew,  which 
have  been  exposed  by  the  removal  of  the  strata  in  which  they  were 
formerly  buried.  A  photograph  of  this  ancient  forest  is  presented  in  Fiy. 
B,  Plate  14.     The  history  of  this  deposit  of  sand  and  gravel  and  of  tlic 


GLACIEitS    OF   ALASKA. 


87 


forest  entombed  in  it  is  in  brief  as  follows  :  The  glacier  was  formerly  not 
so  extensive  as.  now,  having  undergone  a  retreat  after  a  preceding  peiiod 
of  marked  extension,  and  a  dense  forest  grew  at  least  on  the  sides,  if  not 
in  the  center,  of  the  valley  left  exposed  below  its  terminus.  Coincident 
with  the  retreat  of  the  glacier  and  the  growth  of  the  forest  there  must 
have  been  an  elevation  of  the  land  which  excluded  the  water  from  a  por- 
tion of  the  inlet  now  submerged.  While  the  forest  v/as  still  standing, 
tJie  stieams  from  the  glacier,  then  terminating  in  the  valley  to  the  north, 
brought  down  large  quantities  of  gravel  and  sand  and  built  up  an  alluvial 
cone  about  the  extremity  of  the  ice.  As  this  alluvial  cone,  which  proba- 
bly ended  in  the  sea  and  in  fact  was  in  part  a  delta,  increased  in  size,  it 
invaded  the  adjacent  forest  and  buried  the  still  upright  trees.  A  subse- 
quent advance  of  the  glacier  caused  the  ice  to  override  the  gravel  with  its 
entombed  forest.  When  the  glacier  once  more  retreated  the  deposits  were 
uncovered  and  cut  away  by  streams  flowing  from  the  ice,  so  as  to  expose 
.  the  trees  buried  within  their  mass.  This  last  step  in  the  history  of  the 
inlet  is  still  unfinished.  The  terminus  of  the  glacier  is  still  receding,  and 
as  the  streams  flowing  from  it  are  still  excavating  channels  through  tlie 
gravel,  it  is  to  be  expected  that  additional  portions  of  the  buried  forest 
will  be  uncovered.  In  the  moraines  far  up  on  the  surface  of  the  glacier 
and  on  the  islands  of  rock  that  project  above  its  surface,  there  are  bleached 
and  water-soaked  branches  and  trunks  of  trees,  which  show  that  the  now 
desolate  mountains  bordering  the  ice  vere  formerly  more  or  less  forest- 
covered. 

The  process  by  which  forests  about  the  extremities  of  glaciers  became 
buried  in  alluvial  cones  may  be  observed  at  Norris  glacier  and  about  the 
expanded  extremity  of  Davidson  glacier,  but  is  illustrated  in  a  far  more 
striking  manner  alonf^  the  bordei-s  of  Malaspina  glacier,  to  be  described  on 
a  subsequent  page.^ 


''IS^ 


I  i 


Characteristics  of  the  Glacier's  Surface.  —  At  the  locality  on  the 
east  side  of  Muir  inlet,  where  excursionists  usually  land,  the  sul;glacial 
gravels  described  above  are  well  exposed.  The  border  of  the  glacier  and 
the  character  of  the  ice  at  the  extremity'  where  it  overhangs  the  sea  may 

1  The  literature  bearing  on  the  gravel  deposits  and  buried  forests  at  Muir  glacier  may  be 
found  as  follows  :  G.  Frederick  Wright,  "  Ice  Age  in  North  America,"  pp.  58-03,  also  in 
American  Geologist,  vol.  8,  pp.  .330,  331.  H.  P.  Cushing,  American  Geologipt,  vol.  8,  pp.  207. 
I.  C.  Russell,  American  Geologist,  vol.  9,  pp.  190-197.  II.  Fielding  Reid,  National  Geo- 
graphic Magazine, vol.  4,  pp.  38,  40,  pi,  12.  I.  C.  Hussell,  "The  Induence  of  Ddbris  on  the 
Flow  of  Glaciers,  "  Jour.  Geol.,  vol.  3,  1895,  pp.  823-832. 


88 


GLACIERS    OF    NORTH    AMERICA. 


also  be  examined,  and  the  broad  surface  of  the  ice  that  fills  the  valley 
e.'isily  reached.  After  walkiiig  over  the  surface  of  the  ice  between  long 
lines  of  moraines,  where  it  is  as  level  and  smooth  as  a  v/ell-kept  pavement, 
one  may  climb  a  rocky  promontory  on  the  side  of  Mt.  Wright,  and  obtain  a 
wide-reaching  view  of  the  remarkable  scene  that  lies  spread  out  before 
him.  There  is  not  a  tree  or  shrub  in  sight,  but  the  crevices  between  the 
rocks  are  bright  with  alpine  flowers.  The  many  streams  of  snow-covered 
ice  that  unite  to  form  the  main  trunk  glacier  may  be  distinctly  traced 
for  a  score  or  more  of  miles  to  their  sources  in  the  deep  vallt^s  and  am- 
phitheatres in  the  surrounding  mountains.     With  the  aid    of   the   map 


FiO.  8. —Side  View  of  a  ^Iedial  Moraine,  Muib  Glacier.    Photograph  by  H.  B.  Loomis. 

published  by  Prof.  Keid,  reproduced  on  a  reduced  scale  on  Plate  12,  one 
can  obtain  a  most  graphic  idea  of  the  entire  system  of  ice  drainage  termi- 
nating in  Muir  inlet.  The  area  of  the  actual  ice  surface  in  view  is  about 
350  square  miles.  The  total  area  from  which  the  ice  drainage  is  derived 
is  not  far  from  800  square  miles. 

Looking  down  on  the  glacier  from  an  elevated  station,  for  the  first 
time,  one  is  filled  with  awe  and  wonder  at  the  vastness  of  the  panorama  so 
clearly  and  distinctly  visible.  The  rough  broken  ice  with  shining  pinna- 
cles overlooking  blue  crevasses,  in  the  central  portion  of  tLo  stream,  just 
before  it  makes  its  final  plunge  into  the  sea,  reveals  the  line  of  greatest 
movement.  It  was  in  this  call  but  impossible  portion  of  the  glacier  that 
Prof.  Reid  after  great  exertion  placed  his  signals  in  1891,  and  measured 


(iLAflKHS  <IK  XuIlTII    AMKKK  A. 


I'LATK   14. 


Fig.   a.  — surface    OF    MUIR    GLACIER;    WITH    WHITE   GLACIER,    A 

TRIBUTARY. 

(Photograplr  by  H.  1"'.  Ueid.) 


Fig.   B.— buried    FOREST   AND   GRAVEL   DEPOSITS   AT   END   OF 

MUIR   GLACIER. 

(Pliotogrnph  hy  JI.  F.  Keid.) 


the 

iiol 

1)01 

lull 

SIM 
Avll 
JK); 
tlil 
Stil 

rea 
she 
wh 

sta 
tlil 
anc 

var 
fillt 
tail 

cur 
twc 
beg 
apt 
reg 
bar: 

by 

onl 

By' 

ice 
slop 

sho 
Wh 
fina 
exp 
stre 


GLACIERS   OF    ALASKA. 


89 


the  strength  of  the  glacial  current.     The  actual  center  of  the  glacier  was 
not  reached,  however^  as  the  ice  was  there  so  shattered  as  to  he  impassable. 

The  number  of  narrow  dirt-covered  ridges  running  parallel  with  the 
border  of  the' glacier,  and  extending  from  the  summits  of  the  cliffs  over- 
hanging the  sea,  up  the  surface  until  they  disappear  beneath  the  neve 
snow  of  the  higher  regions,  or  reach  rocky  islands  in  the  glacier  from 
which  they  originate,,  mark  the  border  of  the  individual  ice  streams  com- 
posing the  main  and  highly  com[)ound  central  trunk  in  which  all  of  the 
tributaries  unite.  We  note,  also,  that  the  long,  narrow  moraine  belts 
stand  in  relief  above  the  general  surface  like  railroad  embankments.  In 
reality  these  huge  piles  of  stones  and  earth,  as  they  appear,  are  but  a  thin 
sheathing,  covering  ridges  of  ice  which  they  have  preserved  from  melting 
while  the  general  surface  wasted  away. 

Fully  a  score  of  secondary  glaciers  are  in  sight  from  the  elevated 
station  on  which  the  reader  is  supposed  to  stand,  but  there  are  still  other 
tributaries  to  the  eastward  that  are  concealed  from  view  by  Mt.  Wright 
and  neighboring  elevations. 

With  the  accompanying  map  in  hand,  one  may  readily  identify  the 
various  features  of  the  vast  landscape.  One  evident  fact  is  that  the  ice 
fills  the  valleys  to  a  depth  of  many  hundred  feet,  leaving  the  steep  moun- 
tain sides  above  the  established  grade  almost  free  of  snow. 

The  medial  moraines  coming  from  the  northeast  in  broad  graceful 
curves,  as  indicated  on  the  map,  do  not  seem  to  be  formed  by  the  union  of 
two  marginal  moraines,  as  is  the  rule  in  such  instances,  but  appear  to 
begin  suddenly  in  the  region  bordering  Main  and  Berg  lakes.  This 
apnarent  anomaly  is  due  to  the  fact  that  the  secondary  glaciers  in  that 
region  are  wasting  away  and  have  already  melted  at  their  sources  and  left 
barren  boulder-strewn  areas,  now  filled  in  part  with  water  held  in  check 
by  ice  still  filling  the  main  valley.  These  secondary  glaciers  have  not 
only  been  beheaded^  but  a  reverse  flow  initiated  in  the  portion  remaining. 
By  observing  the  contour  lines  drawn  oii  the  map  where  they  cross  the 
ice  in  Main  valley,  it  will  be  seen  that  the  surface  of  the  glacier  has  a 
slope  both  east  and  west  from  a  divide. 

The  most  remarkable  feature  in  the  behavior  of  the  medial  moraines 
shown  on  the  map  is  the  union  of  several  trains  of  stones  and  dirt  on 
White  glacier  and  on  Southeast  tributary,  where  they  come  together  and 
finally  form  a  single  ridge.  This  peculiar  phenomenon  has  not  been  fully 
explained,  but  is  probably  due  to  a  decrease  in  volume  of  the  several 
streams  by  reason  of  their  jpelting.  ^ 


90 


GLACIERS    OF    NORTH    AMERICA. 


Dying  glacier,  on  the  west  side  of  Muir  inlet,  presents  decisive  evi- 
dence of  recent  retreat.  Its  surface  is  almost  completely  concealed 
beneath  dirt  and  stones,  and  the  valley  l»olow  its  present  terminus  has 
recently  l>een  abandoned  by  th<'  'ce  and  is  barren  and  desolate.  Similai' 
evidence  of  the  general  waste  and  recession  that  is  affecting  many  of  tlu; 
glaciers  o''  Alaska  is  also  manifest  in  Dirt  glacier.  In  this  case  the  ice  is 
so  completely  concealed  by  a  superficial  sheet  of  debris  that  one  not  familiar 
with  the  various  phases  of  glacial  waste  would  scarcely  recognize  it  as  a 
f^lacier  at  all.  It  appeai-s  more  like  a  plowed  field  washed  by  winter 
storms  than  like  an  ice  body. 


Recent  Recession. — In  addition  to  the  qualitative  evidence  of  general 
glacial  retreat  indicated  above,  we  have  direct  quantitative  measures  of 
the  recession  of  the  ice  cliffs  in  which  Muir  glacier  ends.  As  observed 
by  Wright  and  Reid,  Muir  glacier  has  in  recent  years  been  both  of  greater 
and  of  less  extent  than  at  present.  The  fact  of  a  former  shrinking  is  shown 
by  an  abundance  of  evidence.  The  bases  of  the  enclosing  mountains  and 
the  summits  of  the  rocky  islands  in  the  glacier  are  smoothed  and  striated, 
and  have  boulders  of  various  kinds  of  rocks  scattered  over  their  slopes. 
These  results  of  ice  action  reach,  in  vertical  height,  about  2000  feet  on  the 
sides  of  the  mountain  near  where  Muir  glacier  now  terminates,  and  extend 
far  south  along  the  shore  of  Glacier  bay.  The  absence  of  trees,  and  the 
general  desolation  of  the  borders  of  Glacier  bay  and  of  all  the  valleys  open- 
ing from  it,  are  in  marked  contrast  to  the  densely  wooded  shores  of 
neighboring  inlets,  and  are  due  to  the  recent  occupation  of  the  region  by 
glacial  ice. 

If  the  ice  at  the  locality  where  Muir  glacier  now  ends  were  2000  feet 
thicker  than  at  present,  making  its  total  depth  about  3000  feet,  as  was  the 
case  when  its  maximum  extension  occurred,  it  is  evident  that  its  terminus 
would  be  far  to  the  south.  At  the  time  of  the  greatest  extension,  all  of 
the  glaciers  now  pouring  into  Glacier  bay  were  united  and  formed  a  trunk 
stream  which  flowed  southward  and  probably  united  with  other  similar  ice 
sheets  so  as  to  form  a  piedmont  glacier.  This  great  extension  was  during 
one  of  the  later  maxima  of  the  glacial  epoch.  There  is  evidence,  how- 
ever, of  an  extension  of  the  ice  far  beyond  its  present  limits  within  the 
past  one  hundred  years. 

In  1794,  Vancouver  sailed  through  Icy  strait  and  failed  to  discover 
what  is  now  known  as  Glacier  bay,  but  states  that  a  wall  of  ice  existed  at 
its  present  entrance.     The  evidence  that  Va^co'ivcr  actually  saw  the 


GLACIERS   OF   ALASKA. 


91 


Uirminus  of  the  Glacier  bay  ice  sheet  is  not  conclusive,  as  his  description 
would  apply  equally  well  to  a  jam  of  bergs  closing  the  entrance  of  the 
inlet.  When  taken  in  connection  with  similar  evidence  of  ice  extension 
in  Disenchantment  bay,  150  miles  to  the  west,  it  seems  reasonable  to 
.suppose,  however,  that  at  the  time  of  Vancouver's  visit  Glacier  Iwiy  was 
actually  occupied  by  a  great  glacier. 

Olwervations  on  the  position  of  the  terminus  of  Muir  glacier  made  by 
Muir  in  1879,8how  that  the  ice  then  extended  about  one  and  three-fourths 
miles,  and  when  seen  by  Wright  in  1886,  about  one  mile  below  the  posi- 
tion of  its  extremity  when  surveyed  by  Reid  in  1890.  Still  more  recent 
observations  indicate  that  this  rapid  retreat,  with  many  variations  in  the 
trend  of  the  ice  cliffs,  is  still  in  progress.^ 


Glaciers  on  the  West  Side  of  Glacier  Bay. 

But  little  is  known  of  the  glaciera  entering  Glacier  bay  from  the  west, 
excepting  that  they  are  of  large  size  and  set  vast  quantities  of  ice  afloat. 
The  thunder  of  avalanches  in  that  region  may  be  heard  while  ascending 
the  bay,  but  the  ice  floes  about  the  fronts  of  the  glaciers  are  usually  so 
closely  packed  that,  so  far  as  I  have  been  enabled  to  learn,  no  vessel  has 
made  a  near  approach  to  them.  Muir  explored  this  portion  of  tlie  bay  in 
a  canoe,  and  states  that  next  to  Muir  glacier,  the  largest  ice  stream  enter- 
ing it  is  at  the  northwestern  extension.  The  glacier  referred  to  is  proba- 
bly the  one  now  known  as  Pacific  glacier.  As  described  by  Muir,  "  its 
broad,  majestic  current,  fed  by  unnumbered  tributaries,  is  divided  at  the 
front  by  an  island,  and  from  its  long,  blue  wall  the  icebergs  plunge  and 
roar  in  one  eternal  storm,  sounding  day  and  night,  winter  and  summer, 
and  from  century  to  century." 

The  glaciers  on  the  west  side  of  Glacier  bay  present  a  most  attractive 
field  for  study  and  are  within  easy  reach  of  lines  of  summer  travel. 
Results  as  valuable  as  those  gathered  by  Wright  and  Reid  might  there  be 
had  during  one  or  two  summer  excursions.^ 

Another  tide-water  glacier  is  reported  to  exist  at  the  head  of  Dundas 
bay,  opening  into  Cross  sound  to  the  west  of  Glacier  bay,  but  there  are  no 
authentic  observations  available  concerning  its  character  and  extent. 

^  A  discussion  of  observations  bearing  on  the  rate  of  retreat  of  Muir  glacier  is  given  by 
Reid  in  The  National  Geographic  Magazine,  Washington,  D.C.,  vol.  4,  1802,  pp.  37-42. 

'  Since  this  was  written  I  have  learned  that  Reid  made  a  study  of  the  glaciers  on  ^he 
west  side  of  Glacier  bay  in  1892.  An  account  of  these  observations,  together  with  a  valuable 
map,  showing  all  of  the  glaciers  that  reach  the  sea  in  that  region,  will  soon  be  published  in 
the  10th  Annual  Report  of  the  U.  S.  Geological  Survey. 


02 


OLACIEK8   OF    NOUTH    AMEKICA. 


Proceeding  Wtjstward  from  CrosH  sound  along  the  Hublime  Fairweathei' 
coaat,  the  next  ghicier  met  witli  which  discharges  directly  into  the  sea,  is 
at  the  head  of  Disenchantment  bay,  150  miles  from  Muir  glacier  and  about 
60  miles  eastward  of  Mount  St.  Elias. 


Glaciehs  of  Disenchantment  Bay. 

(See  map  forming  Plate  17.) 

On  the  shore  of  the  narrow,  winding  inlet  at  the  head  of  Yakutat  bay, 
known  as  Disenchantment  bay,  there  are  three  glaciei-s  which  enter  the 
water  and  give  origin  to  bergs,  and  at  lejist  a  score  of  lesser  ice  streams 
that  have  recently  shrunken  and  are  now  separated  from  the  bay  by 
narrow  and  exceedingly  barren  bouhler-strewn  areas.  On  the  higher 
poitions  of  the  mountains  enclosing  this  land-locked  arm  of  the  sea,  there 
are  hundreds  of  al[)ine  glaciers  descending  from  shining  snow  fields.  The 
tide-water  glaciers  referred  to  are  the  Turner,  Hubbard,  and  Nunatak. 
The  positions  of  their  extremities  are  shown  approximately  on  the  sketch 
map  forming  Plate  17. 

Turner,  Hubbnr<l,  and  Nunatak  Glaciers.  —  The  best  general  idea 
of  the  ice  streams  discharging  into  Disenchantment  bay  can  be  obtained 
from  the  islands  that  break  its  surface.  The  largest  of  these,  named 
Haenke  island  in  honor  of  the  botanists  of  Malaspina's  expedition,  durinpf 
which  portions  of  the  southern  coast  of  Alaska  were  explored  in  1792,  was 
visited  by  the  write  •  in  1890,  and  a  landing  effected  with  some  difficulty 
through  the  closely  packed  icebergs  that  beset  its  shores.  Its  bordere  are 
high  and  rocky.  Its  surface  has  been  worn  into  rounded  and  subdued 
contour  by  the  ice  that  once  flowed  over  it,  with  a  depth  of  about  2000 
feet.  The  domes  of  light-colored  granite  are  smooth  and  polished,  and 
give  abundait  evidence  of  the  stubborn  resistance  they  offer  to  the  ice 
current.  Tne  summit  of  the  island  is  about  800  feet  above  the  surround- 
ing waters. 

The  follo''  :ng  account  of  the  tide-water  glaciers  to  be  seen  from 
Haenke  island  is  taken  from  the  report  of  my  first  expedition  to  Mount 
St.  Elias  :  1 

"  Reaching  the  topmost  dome  of  Haenke  island,  a  wonderful  panorama 
of  snow-covered  mountains,  glaciers,  and  icebergs  lay  before  us.  Tlu; 
island  occupies   the  position  of  the  stage  in   a   vast  amphitheatre;  the 

1  National  Geographic  Magazine,  Washington,  D.C.,  vol.  3,  pp.  08,  99. 


■'  3  1 1 


0LACIEU8   OF   ALASKA. 


98 


spectator  were  hoary  mountain  peaks,  each  a  monarch  robed  in  ermine 
and  bidding  detiance  to  the  ceaseless  war  of  the  elements.  How  insignifi- 
cant the  wanderer  who  confronts  such  an  audience,  and  how  weak  his 
effort  to  descrilH)  snch  a  scene ! 

"  From  a  wild  cliff-enclosed  valley  toward  the  north,  guarded  by  tower- 
ing pinnacles  and  massive  cliffs,  flows  a  great  glacier,  the  fountains  of 
which  are  far  back  in  the  heart  of  the  mountains  Ixjyond  the  reach  of 
vision.  Having  vainly  sought  an  Indian  name  for  this  ice  stream  I 
clnistened  it  Dalton  [Turner]  glacier.*  The  glacier  is  greatly  shattered  and 
])iiuiacle(l  in  descending  its  steej)  channel,  and  on  reaching  the  sea  it  ex- 
jjiinds  into  a  broad  ice  foot.  The  last  steej)  descent  is  made  just  l)efore 
gaining  the  water,  and  is  marked  by  crevasses  and  pinnacles  of  magnifi-. 
cent  proportions  and  beautiful  color.  This  is  one  of  the  few  glaciei-s  of  the 
Mount  St.  Elias  region  that  has  well-tlefined  medial  and  lateral  moraines. 
At  the  base  of  the  cliffs  on  the  western  side  there  is  a  broad  lateral  moraine, 
and  in  the  center,  looking  like  a  winding  road  leading  up  the  glacier, 
runs  a  triple-banded  ribbon  of  debris,  forming  a  typical  medial  moraine. 
The  morainal  material  carried  by  the  glacier  is  at  last  deposited  in  the  sea 
at  its  foot  or  floated  away  by  icebergs  and  scattered  far  and  wide  over  the 
l)()ttom  of  Disenchantment  and  Yakutat  bays. 

"  The  glacier  expands  on  entering  the  water,  as  is  the  habit  of  all 
glacier's  of  clear  ice  when  unconfined,  and  ends  in  magnificent  ice  cliffs 
some  two  miles  in  length.  The  water  dashing  against  the  bases  of  the 
cliffs  dissolves  them  away,  and  the  tide  tends  to  raise  and  lower  the 
expanded  ice  foot.  The  result  of  these  agencies  and  of  the  onward  flow 
of  the  ice  itself  is  to  cause  huge  masses,  sometimes  reaching  from  summit 
to  base  of  the  cliffs,  to  topple  over  into  the  sea  with  a  tremendous 
crash.  Owing  to  the  distance  of  the  glacier  from  Haenke  island,  we 
could  see  the  ice  fall  long  before  the  roar  it  caused  reached  our  eai"8  ;  the 
cliffs  separated  and  huge  masses  seemed  to  sink  into  the  sea  without  a 
sound  ;  the  spray  thrown  up  as  the  blue  pinnacles  disappeared  ascended 
like  gleaming  rockets,  sometimes  as  high  as  the  tops  of  the  cliffs,  and  then 
fell  back  in  silent  cataracts  of  foam.  Then  a  noise  as  of  a  cannonade 
came  booming  across  the  waters  and  echoing  from  cliff  to  cliff.  The  roar 
of  the  glacier  continues  all  day  when  the  air  is  warm  and  the  sun  is  brght, 
and  is  most  pronounced  when  the  summer  days  are  finest.  Sometimes 
roar  succeeds  roar  like  artillery  fire,  and  the  salutes  were  answered,  gun 

*  The  U.  S.  Board  of  Geographic  Names  has  for  sufficient  reason  authorized  the  substi- 
tut  ion  of  the  name  of  J.  H.  Ihiruer  for  the  name  originally  given  by  me. 


fv 


■r 


!  '  11 


I';' 


94 


OLACIKItb    OF    NUKTH    AMKItlCA. 


for  gun,  by  the  greut  'iul)l)iinl  gliu  i«!r,  which  [uniVH  itH  flood  of  ice  into 
the  fiord  a  few  miles  uortlieivst  of  where  Turner  glacier  terminates.  This 
ice  stream,  the  most  magnilicent  of  the  tide-water  glaciers  of  Alaska  yet 
discovered  (with  the  exception,  as  is  now  known,  of  the  southwest  pro- 
longation of  Malaspina  glacier),  and  a  towering  mountain  peak  from  which 
it  receives  a  large  [)art  of  its  drainage, were  named  in  honor  of  (Jardiucr 
(f.  IIul)l)ard,  president  of  the  Natioiial  (ieographic  Society.  A  dark  head- 
hmd  on  the  shore  of  the  mainland  to  the  right  slnits  off  the  full  view  ot 
the  glacier,  hut  formed  a  strongly  drawn  foreground,  which  enhanced  the 
pictures(iue  effect  of  the  scenery." 

A  year  later,  on  September  0,  I  renewed  the  exploration  of  Disenchant- 
jiient  bay.  With  two  c()m[)anions  I  rowed  northward  near  the  base  of  the 
cliff's  to  the  east  of  Ilaenke  island.  We  found  the  bay  quite  free  from 
floating  ice,  although  the  bergs  were  densely  packed  against  the  western 
snore.  The  morning  was  bright  and  fresh  after  prolonged  storms,  but 
dense  cloud  masses  still  clung  to  the  coM  summits  of  the  higher  moun- 
tains. The  vegetation  on  the  rugged  shores  became  more  and  more 
stunted  as  we  advanced.  Before  reaching  Osier  island,  situated  at  tlic 
abrupt  angle  formed  where  Disenchantment  bay  turns  eastward,  even  tlic 
more  sheltered  gorges  were  barren  and  desolate  down  to  within  100  fctt 
of  the  water's  edge.  At  Osier  island  there  is  an  outstanding  cape,  form- 
ing an  island  at  high  tide,  which  is  covered  with  a  dense  growth  of 
stunted  willows,  —  hence  its  name,  —  and  affords  a  fine  station  for  ol)- 
serving  the  magnificence  of  the  surrounding  glaciers  and  mountains. 

Seated  among  the  willows  on  the  summit  of  the  island,  we  noted  the 
luxuriance  of  the  grasses  at  our  feet  and  the  profusion  of  dwarf  rasp- 
berries, Jiubus  arctica,  which  were  just  ripening.  We  were  at  the  actual 
border  of  vegetation.  All  to  the  north  was  stern,  wild,  and  desolate. 
Cliffs  and  precipices  without  the  so^u^ning  tints  of  plant  life  rose  precij)i- 
tously  from  the  water's  edge  tc  ':l>i.  snow-covered  slopes  which  disa^)- 
peared  in  the  clouds.  Just  across  the  inlet,  perhaps  two  miles  distant, 
rose  the  ice  cliffs  of  Hubbar '  glacier  to  a  height,  by  estimate,  of  250  to 
300  feet.  Each  shining  buttress  and  glittering  pinnacle,  as  seen  in  the 
early  morning  light,  was  of  the  purest  white  or  of  the  most  delicate  blue, 
while  the  caves  and  deep  recesses  were  of  such  a  deep  blue  that  they 
appeared  black  in  contrast  with  the  sheen  of  the  surfaces  where  the  sun- 
light fell.  Reports  like  the  roar  of  heavy  guns  frequently  attracted  our 
attention  to  the  cliffs,  but  owing  to  their  distance,  the  avalanches  causiut,' 
the  disturbances  usually  disappeared  before  the  sound  reached  our  station. 


ULAdKHIt  or  NollTII   A.MKUUA. 


Tlatk  is. 


Fig.   a  —HUBBARD   GLACIER,    DISENCHANT^;FNT    BAY,   ALASKA. 
«I*rii\i'n  from  n  I'liotograiili.) 


Fig.   B.- glaciated    SURFACE    OF    HAENKE    ISLAND,   DISENCHANTMENT    BAY, 

ALASKA,    LOOKING    NORTH. 


\ 


GLACIKRS   OF   ALASKA. 


9o 


Following  the  reports  came  the  waves  generated  by  the  falling  ice  masses, 
which  broke  on  the  beach  in  long  lines  of  foam.  The  surface  of  the 
bay  was  unruffled  by  wii;d,  and  the  breaking  of  these  occasional  surges 
seemed  a  phenomenon  wiihout  a  cause,  until  their  connection  with  the 
masses  of  ice  falling  from  the  glacier  was  suggested. 

Both  Turner  and  Hubbard  glaciers  are  in  full  view  from  Osier  island, 
as  are  also  many  lessci'  ice  streams  that  do  not  reach  the  sea.  The  lower 
extremity  of  all  of  the  smaller  glaciers  that  approach  the  sea  are  com- 
l)le<^ely  concealed  beneath  brown  and  barren  moraines.  Many  times  these 
sheets  of  debris  are  so  uniform,  and  merge  with  the  surrounding  boulder- 
covered  area  so  gradually,  that  it  is  impossible  to  tell  where  the  glaciers 
actually  terminate. 

During  our  exploration  of  Disenchantment  bay,  we  sailed  eastwaid 
along  the  coast  to  where  the  inlet  abrujjtly  clianges  its  coui-se  and  extends 
southward  through  the  mountains  and  into  the  flat,  fo^ast-covered  alluvial 
plain  bordering  the  Pacific.  At  the  angle  where  the  bay  makes  this  sharp 
bend  there  is  a  high,  rocky  promontory  of  glacier-burnished  rock,  which  I 
'laraed  Cape  Enchantment.  From  the  summit  of  this  headland  another 
splendid  view  of  the  mountain-enclosed  bay  was  obtained.  At  the  extreme 
eastern  end  of  the  easc-and-west  reach  of  the  bay,  a  large  glacier  comes 
down  to  the  water,  and  breaking  off  sends  many  bergs  adrift.  This 
glacier  was  not  explored,  but  evidently  flows  from  snow  fields  far  back  in 
the  highlands.  Near  where  it  discharges  into  the  bay  it  is  divided  by  a 
rounded  dome  of  rock  which  rises  through  the  ice  and  forms  a  nunatak, 
as  such  islands  in  ice  are  cjilled  in  Greenland,  which  suggested  the  name 
Nunatak  glacier. 

Many  other  facts  of  interest  to  the  student  of  glaciers  ma}'^  be  observed 
from  Haenke  and  Osier  islands  and  from  Cape  Enchantment,  some  of 
which  are  described  elsewhere.^  As  our  immediate  interest  is  concen- 
trated on  tide-water  glaciers  we  must  pass  on,  in  our  fireside  travels,  to  the 
next  example,  to  the  west  of  Yakutat  bay,  which  is  by  far  the  most 
magnificent  of  its  class  yet  found  in  Alaska. 


Icy  Cape. 

All  of  the  tide-water  glaciers  of  Alaska  referred  to  above  reach  the 
waters  of  the  ocean  at  the  heads  of  deep  inlets  or  fiords,  and  are  sur- 

i"An  Expedition  to  Mount  St.  Elias,  1800,"  National  Geograpiiic  Magazine,  vol.  A, 
1391,  pp.  53-203.  "  Second  Expedition  to  Mount  St.  Ellas,  1891,"  13th  Annual  Report  U. 
S.  Geological  Survey,  pp.  1-01. 


96 


GLACIERS   OF   NORTH   AMERICA. 


rounded  by  precipitous  mountains.  At  Icy  cape,  however,  the  western 
lobe  of  Malaspina  glacier  advances  boldly  into  the  Pacific  and  meets  the 
full  force  of  its  surges.  There  are  no  highlands  bordering  the  ocean  foi- 
scores  of  miles  on  either  hand,  and  the  glittering  wall  of  ice  rises  above 
ihe  foaming  waters  to  a  height  not  less  than  three  hundred  feet.  The 
general  appearance  of  these  great  precipices  of  ice  when  seen  at  a  distance 
recall  the  chalk  cliffs  of  Dover,  but  are  more  varied  in  color  and  far  more 
impressive.  The  heavy  waves  of  the  Pacific  undermine  the  cliffs,  and 
great  masses  of  ice  are  almost  continually  falling  into  the  sea.  Their 
thunder  is  seldom  silent,  and  on  still  days  can  be  heard  distinctly  at  a 
distance  of  twenty  miles. 

The  scene  presented  by  Icy  cape,  with  its  white  girdle  of  floating 
bergs,  especially  when  a  storm  is  raging  and  the  heavy  billows  add  their 
roar  to  the  thunder  of  the  avalanches,  is  one  of  the  wildest  and  grandest 
ihat  can  be  imagined. 

The  ice  ciiffs  formed  where  Malaspina  glacier  enters  the  sea  prese  .t 
only  one  of  th^  many  interesting  features  of  the  great  ice  sheet     .  r 
southern  base  of  Mount  St.  Elias.     This  great  glacier  is  the  type  of  pied- 
mont ice  sheets,  and  will  be  described  a  few  pages  in  advance. 

To  the  west  of  Icy  cape  there  are  other  great  glaciei-s  intervening  be- 
tween the  mountains  and  the  sea.  The  largest  of  these,  known  as  Bering 
glacier,  is  probably  of  the  same  character  as  the  Malaspina  ice  sheet,  but  no 
one  has  trodden  its  surface  and  scarcely  anything  is  known  concerning 
even  its  more  general  features.  So  ^ar  as  has  been  reported,  there  are  no 
glaciers  to  the  west  of  Icy  cape  which  actually  reach  the  sea,  and  there- 
fore none  that  require  mention  at  the  present  time. 


Alpine  Glaciers. 

Several  of  the  alpine  glaciers  of  Alaska  which  enter  the  sea  have 
already  been  partially  descriljed  under  the  head  of  tide-water  glaciers;  but 
there  are  others,  numbering  many  hundred  and  probably  several  thou- 
sand, that  terminate  before  reaching  the  sea,  and  belong  to  the  class  heie 
considered.  Nearly  all  of  the  higher  valleys  and  degressions  among  j;lu' 
mountains  from  Stikine  river  northward  and  westward  to  Cook's  inlet  are 
filled  with  n6vd  snows  and  drained  by  ice  streams.  This  great  glacial 
belt,  nearly  a  thousand  miles  in  length,  has  its  maximum  width  in  the 
vicinity  of  Mounts  Fairweather,  Logan,  and  St.  Elias,  where  it  is  from  80 
to  100  miles  wide.     Over  this  central  territory,  about  350  miles  in  length, 


GLACIERS   OF   ALASKA. 


97 


every  depression  at  an  elevation  of  over  a  thousand  feet,  is  filled  with 
snow  and  ice,  making  one  confluent  neve  field,  through  which  the  higher 
and  more  rugged  peaks  rise  like  barren  islands.  An  extended  view  of 
tliis  wild  country,  where  so  many  glaciers  have  their  sources,  was  obtained 
l)y  the  writer  in  August,  1891,  from  the  northern  side  of  Mount  St.  Elias, 
and  may  be  taken  as  representing  the  general  character  of  the  entire 
region  between  Lynn  canal  and  Copper  river.  My  report  on  the  jjortion 
of  the  climb  referred  to  is  as  follows  ^ : 

"  I  was  now  so  near  the  crest  of  the  divide  that  only  a  few  yards  re- 
mained before  I  should  be  able  to  see  the  country  to  the  north,  a  vast 
region  which  no 'one  had  ^"^et  beheld.  As  I  passed  on,  I  pictured  in  fancy 
its  character.  Having  previously  crossed  this  same  system  of  mountains 
at  the  head  of  Lynn  canal  and  traversed  the  country  north  of  it,  I  imagined 
I  should  behold  a  similar  region  north  of  Mount  St.  Elias.  I  expected  to 
see  a  comparatively  low,  forested  country,  stretching  away  to  the  north, 
with  lakes  and  rivers  and  perhaps  some  signs  of  human  habitation ;  but  I 
was  entirely  mistaken.  What  met  my  astonished  gaze  was  a  vast  snow- 
covered  region,  limitless  in  expanse,  through  which  hundreds  and  perhaps 
thousands  of  barren,  angular  mountain  peaks  projected.  There  was  not  a 
stream,  not  a  lake,  and  not  a  vestige  of  vegetation  of  any  kind  in  sight. 
A  more  desolate  or  a  more  utterly  lifeless  land  one  never  beheld.  Vast 
smooth  snow  surfaces,  without  crevasses,  .'itretched  away  to  limitless 
distances,  broken  only  by  jagged  and  angular  mountain  peaks.  The 
general  elevation  of  the  snow  surface  is  about  8000  feet,  and  the  moun- 
tiiins  piercing  it  are  from  10,000  to  12,000  feet,  or  more,  in  altitude  above 
the  sea.  Northward  I  could  see  every  detail  in  tl  /^  forbidding  landscape 
for  miles  and  miles.  The  most  remote  peaks  in  view  in  that  direction 
were  40  or  50  miles  distant.  To  the  southeast  rose  Mount  Fairweather, 
ilainly  distinguishable,  although  200  miles  away.  About  an  equal  dis- 
:^ce  to  the  northwest  are  two  prominent  mountain  ranges,  the  highest 
[h  aks  of  which  appeared  as  lofty  as  Mount  Fairweather.  These  must  be 
in  the  vicinity  of  Mount  Wrangel,  but  their  summits  were  unclouded 
and  gave  no  token  of  volcanic  activity. 

"I  could  look  down  upon  the  coast  about  Yakutjit  bay  and  distin- 
i^uish  each  familiar  island  and  headland.  The  dark  shade  on  the  shore, 
too  distant  to  reveal  its  nature,  I  knew  was  due  to. the  dense  forests  on 
the  lowlands  between  the  mountains  and  the  sea.     This  was  the  only 

1 "  Second.Expedition  to  Mount  St.  Elir  ?,  1801,"  in  13th  Annual  Report  U.  S.  Geologi- 
cal Survey,  1891-02,  pp.  47,  48. 


98 


GLACIEIIS    OF    NOUTII    AMERICA. 


indication  of  vegetation  in  all  the  vast  landscape  that  lay  spread  out 
beneath  my  feet.  The  few  rocks  near  at  hand,  which  projected  above  the 
snow,  were  without  the  familiar  tints  of  mosses  and  lichens.  Even  the 
ravens  which  sometimes  haunt  the  higher  mountains  were  nowhere  to  be 
seen.     Utter  desolation  claimed  the  entire  land. 

"  The  view  to  the  north  called  to  mind  the  pictures  given  by  Arctic 
explorers  of  the  borders  of  the  great  Greenland  ice  sheet,  where  rocky 
islands,  known  as  '  nvniataks,'  alone  break  the  monotony  of  the  boundless 
sea  of  ice.     The  region  before  me  was  a  land  of  nunataks." 

^t  is  impossible  to  give  a  detailed  account  of  the  great  number  of 
ali)ine  glaciers  in  southern-  Alaska,  but  a  few  of  those  "best  known  may 
be  described,  and  serve  as  examples  of  the  class  to  which  they  belong. 


.iL 


Seward  Glacier.  —  The  largest  alpine  glacier  thus  far  discovered  in 
North  America,  exclusive  of  the  Greenland  region,  has  its  source  in  the 
neighborhood  of  Moun*:  Logan,  and  was  named  the  Seward  glacier  in 
honor  of  the  distinguished  Secretary,  to, whom  we  are  indebted  for  the 
jnirchase  of  Alaska.  It  has  many  tributaries  in  the  rugged  region  where 
it  rises,  and  flows  southward  like  a  broad  sluggish  river  to  the  ?Ialasi)ina 
glacier,  of  which  it  is  one  of  the  principal  feedei-s.  A  portion  of  this  great 
glacier  and  some  of  its  branches,  is  shown  on  the  map  forming  Plate  16, 
but  the  entire  area  it  drains  has  not  been  explored.  A  view  of  the  glacier 
and  of  many  of  its  tributaries  was  had  b}'  the  writer  from  the  summit  of 
the  Pinnacle  cliffs,  which  embraced  fully  fifty  miles  of  the  ice  stream  and 
nipuy  of  the  magnificent  peaks  from  which  it  receives  the  snow  drainage. 
The  jjlacier  in  its  narrowest  part  is  by  estimate  three  miles  broad.  Ex- 
cept at  a  few  places  where  it  passes  rocky  precipices,  its  sides  are  poorly 
defined,  as  it  merges  with  broad  snow  fields  in  such  a  manner  that  only 
the  crevassed  and  broken  condition  of  the  snow  en  t'.e  sides  of  the  more 
rapidly  flowing  central  portion  serves  to  define  its  boundaries.  At  tliree 
localities  where  it  descends  steep  slopes  due  to  faults  in  the  rocks  beneath, 
the  ice  is  broken  and  stands  in  pinnacles  between  blue  crevasses,  but 
these  ice  falls  are  not  as  high  or  as  impressive  as  in  some  of  the  neighbor- 
ing glaciers.  The  firat  or  upper  fall,  at  the  east  end  of  the  Corwin  cliffs, 
is  an  abrupt  descent  of  several  hundred  feet,  and  from  the  west  appears 
like  a  huge  wall  crossing  the  glacier  from  side  to  side.  Both  above  and 
below  the  fall  the  surface  appears  nearly  level  for  several  miles,  and  is  as 
smooth  and  even  as  a  snow-covered  meadow.  Some  ten  mil^s  below  t\\v 
upper  fall  is  the  second  ice  cascade,  or  what  may  more  property  be  called 


GLACIEUS   OF    ALASKA. 


99 


an  ice  rapid.  The  ice  is  there  greatly  crevassed  for  several  miles,  but 
letains  a  generally  level  surface  and  its  remarkably  stream-like  character. 
These  rapids  occur  where  the  ice  flows  across  an  escarpment  formed  by  a 
prolongation  of  Pinnacle  cliffs. 

On  looking  down  on  the  rapids  from  a  commanding  summit,  one  be- 
holds a  series  of  breaks  in  the  ice  which  are  small  at  first  and  trend  up 
stream  from  each  margin  of  the  central  current.  The  first  breaks  to  be 
recognized  are  mere  cracks,  and  although  approaching  the  center  of  the 
glacier,  do  not  meet.  A  few  rods  below,  the  cracks  are  a  little  broader, 
and  meet  in  the  center  of  the  glacier  so  as  to  form  a  continuous  break  from 
side  to  side.  The  fissures  from  either  side  meet  at  an  angle  of  perhaps  50 
or  60  degrees,  and  form  V-shaped  figures,  with  their  apexes  pointing  up 
stream.  A  few  rods  farther  down,  the  crevasses  cross  the  glacier  in  nearly 
straight  lines,  and  then  begin  to  bow  in  the  middle  on  account  of  tlie  more 
rapid  central  current.  The  more  rapid  flow  of  the  central  portion  of  the 
stream  is  indicated  throughout  the  descent  by  the  curvature  of  the  crevasses. 
After  becoming  gently  curved  down  stream  they  pass  into  semilunar 
gashes,  widest  in  the  center  and  tapering  towards  the  end.  Finally,  near 
the  lower  end  of  the  rapid,  the  crescents  liecome  sharply  bent  in  the 
center,  and  the  bending  increases  until  the  gashes  from  either  side  unite 
at  an  angle  of  perhaps  30  degrees,  and  again  form  V-shaped  figures,  this 
time  pointing  down  stream.  With  these  progressive  changes  in  the  direc- 
tion and  size  of  the  crevasses,  cross  fractures  are  formed,  which  become 
more  and  more  numerous  in  the  central  and  lower  portions  of  the  rapid. 
The  parallel  V-shaped  gashes  aiTanged  in  regular  order,  one  above 
another,  impart  to  the  central  part  of  the  glacier  a  peculiar  wavy  appear- 
ance when  seen  from  a  distance,  resembling  the  changeable  figures  to  be  seen 
in  "  watered  ribbon."  With  these  changes  in  the  direction  and  size  of  the 
crevasses  there  are  accompanying  changes  in  color.  The  cracks  in  the 
upper  part  of  the  rapids  are  in  a  white  surface,  but  the  ice  forming  their 
walls  is  dark  blue.  At  a  distance  the  breaks  appear  as  blue  lines  on  the 
snow.  Lower  down  stream,  where  the  cracks  become  wider,  broad  Avhite 
tables  are  left  between  them.  As  cross  fractures  are  formed,  the  sides  of 
the  tables  crumble  away  and  portions  falling  into  tl'.e  crevasses  tend  to  fill 
tliem  up.  As  the  surface  melts,  the  surfaces  of  the  tables  lose  their  purity 
and  become  dust-covered  and  yellowish,  but  the  broken  blocks  in  the 
crevasses  expose  fresh  material  and  retain  their  whiteness.  At  this  stage, 
the  sidas  of  the  crevasses  change  from  blue  to  white.  The  positions  of  i;he 
l)reaT,.8  are  then  marked  by  broad,  white  bands  on  a  gray  surface.      Far 


m 


100 


GLACIERS   OF   NORTH   AMEIilCA. 


ill '. 


il 


do'v/i  the  rapids,  where  the  lower  set  of  V-shaped  crevasses  are  most  pro- 
nounced, the  tables  have  crumbled  away  and  filled  the  intervening  gulfs, 
so  that  their  positions  .are  distinguished  solely  by  differences  in  color. 
The  scars  of  the  crevasses  formed  above  are  shown  by  Avhite  bands  on  a 
dark,  dust  and  dirt  covered  surface,  instead  of  by  blue  m.arkings  on  a  white 
surface,  as  at  the  beginning.  Before  the  lower  ice  fall  is  reached  where 
the  Seward  glacier  makes  a  final  plunge  before  joining  the  Malaspina 
glacier,  nearly  all  traces  of  the  tens  of  thousands  of  fissures  formed  above 
have  disappeared. 

An  observer  standing  on  one  of  the  commanding  summits  at  the  western 
end  of  Pinnacle  cliffs  can  see  the  broad  surface  of  Seward  glacier  from 
the  upper  falls  to  where  it  disappears  over  the  brink  of  the  lower  fall  on 
the  border  of  Malaspina  glacier.  The  glacier  from  side  to  side  then  drops 
from  sight,  and  the  wild  assemblage  of  pinnacles  that  occui-s  below  is  only 
indicated  by  a  line  of  blue  where  the  final  plunge  begins.  Such  a  view 
suggests  the  appearance  of  Niagara  when  seen  from  above  the  hoi-seshoe 
fall,  but  the  far  mightier  cascade  in  the  Seward  glacier  is  silent  and 
apparently  motionless. 

The  writer  was  encamped  for  several  days  in  July,  1890,  on  a  narrow 
crest  of  rock  barely  wide  enough  to  support  a  small  tent,  which  breaks 
through  the  snow  at  the  western  end  of  Pinnacle  cliffs ;  and  on  the  imme- 
diate border  of  the  rapids  is  Seward  glacier.  The  murmur  of  water  flow- 
ing through  icy  channels  could  be  heard  far  beneath  the  surface  of  the 
glacier,  but  no  streams  traversed  its  broken  surface.  Crashes  and  rum- 
bling noises  produced  by  the  slowly  movinof  mass  frequently  attracted  our 
attention,  and  sometimes  at  night  Ave  would  be  av/pkened  by  a  dull,  heavy 
thud,  accompanied  by  a  trembling  of  the  rocks  on  whicli  v/e  slept,  and 
producing  the  effect  of  a  slight  earthquake  shock.  Occasionally  a  tower- 
ing pinnacle  of  ice  on  the  extremely  rugged  surface  of  the  glacier  in  front 
of  our  tent  would  fall  with  a  startling  crash  and  be  engulfed  in  an  ad- 
jacent crevass.  These  evidences  of  change  showed  that  the  apparently 
motionless  ice  was  in  reality  flowing  onward.  Changes  in  the  relative 
positions  of  easily  recognized  points  on  the  glacier  and  on  the  distant 
shore  were  noticed  during  various  visits,  but  instrumental  measurements 
of  the  rate  of  motion  of  various  prominent  pinnacles  made  by  my  assistant 
and  myself  failed  to  give  satisfactory  results. 

When  exploration  shall  be  extended  into  the  mountains  clustering 
alxjut  Mount  Logan  and  extending  northward  from  Mount  St.  Elias,  the 
Seward  glacier  will  furnish  the  most  promising  highway  of  travel.     The 


I- 

i ' 


Glaciehs  of  Nobth  Amkuha. 


Plate  16. 


Fig.   a.  — surface   OF    SEWARD   GJ.ACIER,    ALASKA. 

Tlie  suiitmit  of  Mount  St.  E  •<«»  is  seen  in  the  Uistance,  beyonil  the  hills  bordering  the  glacier. 

(l)riiwn  from  a  Photograph.) 


■  r 


Fig.   B.  — DAVIDSON    GLACIER.   LYNN    CANAL,   ALASKA. 


GLACIKUS    OF    ALASKA. 


101 


snow  fields  along  the  margins  of  the  glacier  where  its  surface  is  most 
broken  afford  easy  lines  of  march,  and  the  ice  falls  can  be  })assed  without 
serious  ditliculty  by  scaling  the  adjacent  cliffs.  When  once  above  the 
upper  fall  the  way  is  clear,  and  a  broad,  snow-covered  surface  affords  a 
direct  route  to  the  immediate  base  of  Mount  Logan.  In  making  this 
journey  the  explorer  should  pass  around  the  southern  end  of  the  Hit(di- 
cock  range  and  gain  the  Seward  glacier  just  above  the  lower  fall.  When 
that  point  is  reached  the  way  ahead  is  well  defined.  By  means  of  snow 
shoes  and  sleds  drawn  b}'  dogs, an  advance  can  be  made  for  perhaps  a  hun- 
dred miles  into  the  interior.  By  descending  a  glacier  on  the  northern 
side  of  the  mountains  some  stream  could  be  reached  which  would  c:irry  the 
explorer  again  to  the  coast.  The  clor;^  of  the  winter  season  would  i)rol> 
ably  be  the  best  for  this  attractive  journey,  as  the  crevasses  would  then 
be  deeply  buried,  and  the  rivers  of  the  interior  could  be  reached  in  vime 
to  descend  them  during  the  short  summer. 

Although  Seward  glacier  is  the  largest  ice  stream  yet  discovered  in 
Alaska,  it  does  not  differ  materially  from  many  other's  of  the  same  type 
now  known  to  exist  in  that  region.  It  is  the  only  glacier  in  the  neigh- 
borhood of  Mount  St.  Elias,  however,  which,  so  far  as  known,  heads  far 
back  in  the  mountain  and  flows  through  a  low-grade  pass  to  the  sea.  The 
Hubbard  glacier  may  have  this  characteristic,  but  as  its  gathering-ground 
has  never  been  seen,  its  relation  to  the  mountain  cannot  be  definitelj'^ 
determined.  The  character  of  the  surface  of  the  Seward  glacier  is  shown 
on  Fig.  A,  Plate  16  ;  the  summit  of  the  upturned  mountain-block 
forming  Mount  St.  Elias  is  seen  beyond  the  hills  forming  the  bank 
of  the  glacier. 

The  next  large  ice  stream  to  the  west  of  the  Seward  glacier  is  the  Agassiz 
glacier,  which  drains  the  snow  fields  on  the  south  side  of  the  Augusta 
range  and  the  eastern  slope  of  Mount  St.  Elias.  To  the  west  of  Mount 
St.  Elias  rises  Guyot  glacier,  another  of  the  great  tributaries  that  unite  to 
form  the  Malaspina  ice  sheet,  the  type  of  piedmont  glaciers. 


Glaciers  of  Lynn  Canal. 

It  has  been  the  writer's  good  fortune  to  make  three  trips  through 
Lynn  canal,  each  of  which  furnished  many  independent  observations  on 
the  glaciers  diveraifying  its  shores.  The  first  of  these  journeys  was  made 
in  a  canoe  with  a  single  Indian,  while  returning  from  an  expedition  up 
the  Yukon  river,  an  account  of  which  has  been  published  in  the  Bulletin 


102 


OLACIEUS  OF   NOUTH   AMEUICA. 


of  the  Geological  Society  of  America.^     The  second  and  third  journeys 
were  made  on  steamei-s  and  were  much  less  satisfactory  than  the  first. 

Taya  Inlet.  —  Lynn  canal  divides  near  its  head  into  two  arms,  known 
as  Taya  and  Chilkat  inlets.  The  first  leads  toward  Chilhoot  pass  an<l 
the  second  toward  Chilkat  pass.  Each  of  these  arms,  like  the  main 
trunk  of  Lynn  canal,  is  bordered  by  high  mountains,  and  receives  many 
swift  streams  issuing  from  caves  at  the  lower  extremities  of  alpine 
glaciers.  The  larger  glaciei-s  drain  broad  neve  fields  which  whiten  the 
higher  portions  of  the  mountains  throughout  the  year.  The  smaller  ones 
have  their  sources  in  sheltered  amphitheatres  and  cirques,  but  at  times 
originate  in  snow  fields  that  rest  on  the  mountain  side,  and  are  so  promi- 
nent that  when  seen  in  profile,  they  give  a  convex  outline  to  the  sides  of 
the  peaks  about  which  they  cluster. 

From  a  mountain  top  about  3000  foet  high,  on  the  west  side  of  Taya 
inlet,  I  obtained  an  extensive  and  most  instructiv^e  view  of  the  rugged 
mountains  in  which  the  blue  tranquil  waters  of  the  great  canal  are  em- 
bosomed. From  one  stati  )n  I  counted  nearly  forty  glaciers,  and  a  change 
in  position  of  half  a  mile  brought  several  others  into  view  which  before 
were  concealed  by  rugged  crags  and  snow-covered  slopes  near  at  hand. 
The  outlines  of  vast  amphitheatres  in  the  mountain  tops  could  be  traced  hy 
lines  of  pinnacles  and  towering,  frost-riven  crags  forming  their  rims,  but 
the  basins  within  were  so  deeply  filled  with  snow  and  ice  that  one  could 
walk  across  them  with  ease.  Many  of  the  views  of  the  mountains  enclos- 
ing Lynn  canal,  obtained  from  the  decks  of  steamers,  are  truly  magnifi- 
cent, but  fail  to  give  such  a  comprehensive  idea  of  the  entire  plan  of  the 
hundreds  of  snow-clad  peaks,  and  of  the  deep  valleys  separating  them,  as 
the  broad  panoramas  which  reward  the  climber  who  reaches  some  of  the 
less  aspiring  summits.  Added  to  the  sublime  picture  of  snowy  ranges 
and  winding  waterways  obtained  from  such  a  station  are  wonderful  cloud 
effects,  to  be  seen  especiall}'^  when  a  storm  gives  way  to  clear  skies  and  the; 
last  remnant  of  the  vapory  hosts  that  previously  enshrouded  the  ranges 
still  cling  to  the  more  lofty  summits. 

Davidson  Glacier.  —  The  finest  glacier  on  Lynn  canal,  named  in 
honor  of  Prof.  George  Davidson,  of  the  U.  S.  Coast  and  Geodetic  Survey, 
has  its  source  in  the  rugged  mountains  between  Lynn  canal  and  Glacier 
bay,  and  flows  froia  the  same  general  n^ve  fields  that  supply  some  of  the 
principal  tributaries  of  Muir  glacier.     A  photograph  of  its  expanded  ex- 

1  Vol.  1,  1890,  pp.  99-162. 


GLACIEI'.S   OF   ALASKA. 


108 


tremity,  as  seen  from  a  passing  vessel,  is  reproduced  in  Fig.  H,  Plate  1<>. 
It  finds  its  way  east'vard  through  a  deep,  high-grade  gorge  Injtween  lofty 
peaks,  and  reaches  within  a  few  score  feet  of  sea  level,  hut  does  not  enter 
the  watera  of  the  canal  so  as  to  form  a  title-water  glacier.  Moraines  left 
hy  the  glacier  in  its  retreat,  and  alluvial  material  brought  out  from  it  by 
swift,  heavily  laden  streams,  have  l)een  deposited  about  the  margin  of  the 
ice  foot  so  as  to  form  an  encircling  girdle  now  covered  on  its  outer  margin 
with  a  dense  spruce  forest.  On  passing  from  the  Ixiach  through  the  forest 
for  a  distance  of  about  a  mile,  one  comes  to  a  barren,  desolate  tract  of 
boulders  and  gravel  of  fresh  appearance,  and  evidently  but  recently 
abandoned  by  the  glacier.  The  hirren  area  is  perhaps  half  a  mile  broad, 
and  separates  the  extremity  of  the  foot  of  the  glacier  throughf)ut  the  entire 
periphery  of  its  expanded  terminus  from  the  encircling  forest.  From 
archways  in  the  ice  there  issue  swift,  roaring  streams  of  muddy  water, 
much  too  strong  and  too  deep  for  one  to  w.ade.  These  streams  are  heavily 
loaded,  and  at  once  b^gin  to  deposit  their  burdens  and  to  build  up  their 
channels,  so  that  their  courses  are  unstable  and  new  distributaries  ar;  formed 
from  time  to  time.  Standing  by  the  side  of  one  of  the  streams  as  it  issues 
from  its  icy  cavern,  one  may  hear  the  clash  of  the  boulders  that  are  swept 
along  at  the  bottom  of  the  turbid  waters.  The  localities  at  which  the 
streams  emerge  from  the  ice  are  changed  from  time  to  time,  so  that  the 
entire  area  bordering  the  ice  foot  is  torrent-swept  and  covered  with 
stream-borne  deposits. 

The  ice  at  the  lower  extremity  of  Davidson  glacier  has  a  crystalline 
appearance,  much  like  coarsely  crystallized  dolomite.  The  banded  struc- 
ture generally  so  characteristic  of  glacial  'ce-  is  not  apparent  in  the  ex- 
posed surface*.  On  climbing  the  rough  crags  of  ice  forming  the  immediate 
foot  of  the  glacier  one  finds  stones  and  dirt  scattered  over  its  surface,  but 
a  definite  arrangement  of  the  superficial  debris  in  medial  aid  lateral  mo- 
raines is  not  apparent  in  a  near  view.  From  a  distance,  however,  as  from 
the  decks  of  passing  vessels,  well-characterized  medial  bands  looking  like 
roadways  can  be  easily  recognized,  as  well  as  broad,  dirt-covered  areas, 
answering  to  lateral  moraines,  at  the  bases  of  the  enclosing  cliffs. 

During  my  canoe  trip  down  Lynn  canal  in  1889,  I  was  storm-lx)und 
for  three  days  at  Davidson  glacier,  and  sought  refuge  in  the  somljre,  moss- 
covered  forest  about  its  foot.  One  cannot  fully  appreciate  the  varied 
beauties  of  the  dense  forests  of  Alaska  until  he  has  actually  lived  in  their 
depths  and  witnessed  the  many  changes  that  the  primeval  wilderness  pre- 
sents during  storms  and  sunshine.     The  trees  are  large  and  rugged,  and 


104 


GLACIERS   OF    NORTH    AMERICA. 


frequently  clothed,  even  to  the  ends  of  their  topmost  briiiiehes,  with  dense 
oouts  of  Hhiij,'^'y  nioHH.  Aged  trunks  long  since  dciid  and  stripped  of  their 
foliage,  but  still  standing,  assume  strange,  weird  shapes,  due  to  the  thick 
masses  of  mosses,  lichens,  ajul  fungi  that  make  their  homes  upon  them. 
Mosse!?  and  lichens  cover  the  grouiul  as  with  a  dense  mat  a  foot  or  more 
thick,  into  which  one  sinks  knee-deep  at  every  step  as  if  walking  over  a 
bed  of  wet  sponges.  The  trunks  of  fallen  sachems  of  the  fonssts  an; 
buried  from  sight  by  a  living  mound  of  green  and  brown,  most  artistically 
decorated  with  llowers  and  ferns.  Every  rod  that  one  advances  into  the 
moist  and  fre(piently  mist-tilled  forests  reveals  new  beauties,  and  fascinates 
the  fancy  with  harmonies  of  form  and  color  not  exceeded  by  those  of  the 
moss-draped  cy[)ress  and  live-oak  forests  of  Floriuu. 

Along  the  shores  of  Lyini  canal  eastward  from  Davidson  glacier,  there 
are  other  ice  streams  that  drain  the  shining  snow  fields  on  the  mountains 
and  add  variet}'  and  beauty  to  the  splendid  scenery  of  that  justly  famed 
arm  of  the  sea  ;  but  none  of  them  reach  tide  water.  The  extremities  of 
the  larger  glaciers  are  hidden  behind  fringes  of  forests  growing  on  the 
deposits  laid  down  during  their  slow  retreat.  To  an  observer  on  passing 
vessels,  the  steep,  broken  surfaces  of  the  ice  streams,  as  they  descend  pre- 
cipitous slopes,  may  k^e  seen  above  the  green  of  the  forests  into  whir  \ey 
seen]  to  plunge.     When  the  summits  of  the  mountains  are  enshroi  in 

mis*  the  precipices  of  ice  appear  like  frozen  cataracts  descending  from  the 
clouds.  The  glaciers  of  Lynn  canal  that  rank  next  to  Davidson  glacier  in 
size  and  beauty  are  the  Auk,  Eagle,  Lemon  creek,  and  Juneau.  These 
are  all  on  the  northeastern  shore,  and  are  better  known  than  those  on 
the  opposite  coast  because  of  their  proximity  to  the  beach.  There  are, 
besides,  hundreds  of  nameless  glaciers  that  would  well  repay  individual 
study,  of  which  glimpses  may  be  had  by  those  who  pass  in  a  day. 

Glaciers  of  the  Interior  of  Alaska. 


In  traversing  the  deep  valleys  leading  from  the  head  of  Lynn  canal  to 
Chilkoot  and  Chilkat  passes,  one  sees  small  glaciers  on  the  adjacent 
mountains.  After  passing  the  divide  between  the  waters  flowing  directly 
to  the  Pacific  and  those  tributary  to  the  rivers  of  the  interior,  other 
similar  glaciers  occur  which  descend  the  northern  slope  of  the  mountains. 
The  timber  line  in  the  interior  is  far  below  the  limit  reached  by  the 
glaciers,  and  the  intervening  area  is  barren  and  rugged,  and  strewn  with 
debris  left  by  former  ice  streams.     In  the  clefts  between  the  more  lofty 


CJLAriKKS   OP    ALA8KA. 


106 


summits  rising  above  tho  barren  area,  there  are  tongnes  of  ico  that  (U'seend 
from  snow  fields,  tilling  elevated  valleys  and  amphitheatres  alM)ut  the 
crests  of  tho  mountains.  These  glaciers  all  of  the  alpine  type,  are 
usually  of  comparatively  small  size,  and  are  the  sources  of  many  swift 
streams  of  turbid  water.  Their  extremities  are  seldom  lower  than  8000 
or  4000  feet  above  sea  level. 

The  general  features  of  tlio  region  draining  northward  in  tho  vicinity 
of  Lynn  canal  are  Iwlieved  to  be  characteristic  of  an  extended  l)elt  of  im- 
perfectly explored  country  along  the  iidand  .slope  of  the  mountains 
bordering  the  coast.  Hohl  explorations  nuido  to  tho  westward  of  Chilkat 
pass,  bv  E.  J.  Glave  in  1890,  and  again  in  1801,  show  that  in  the  region 
(Inuned  by  Also k  river  —  a  wild,  imi)etu()us  stream  th)wing  through  the 
mountains  bordering  the  coast  —  and  by  numerous  tributaries  of  the 
Yukon,  there  are  many  ali)ine  glaciers  of  the  same  general  character  as 
those  already  referred  to  at  the  head  of  Chilkat  pa«s. 

Our  knowledge  of  the  glaciers  draining  to  the  interior  was  mucih  ex- 
tended in  the  summer  of  1891  by  important  explorations  made  by  Dr.  C. 
Willard  Hayes  ^  in  com[)auy  with  Lieut.  Frederick  Schwatka.  This  ex- 
pedition ascended  Taku  inlet,  and  after  lossing  a  low  divide  reached  the 
head  watera  of  the  Yukon,  and  descended  that  stream  in  boats  to  Selkirk 
house.  Thence  an  overland  journey  was  made  westward  to  Copper  river, 
and  an  extended  region  explored  on  the  northern  flanks  of  the  mountains 
culminating  in  Mount  Logan  and  Mount  St.  Elias.  On  gaining  Copper 
river  the  expedition  descended  that  stream  to  the  coast,  and  confirmed  the 
report  of  Lieut.  H.  T.  Allen  ^  in  reference  to  the  presence  of  glaciers  near 
the  sea.  The  principal  glaciera  examined  by  Hayes  lie  at  a  distance  of 
50  to  80  miles  to  the  north  and  northwest  of  Mount  St  Elias,  and  are 
described  by  him  as  follows  in  the  paper  just  cited  : 

"Three  large  glaciei-s  flow  into  the  White  River  basin  west  of  the 
Alaskan  boundary;  and  numerous  streams,  crossed  while  following  the 
southern  bank  of  the  upper  White  river,  rise  in  small  glaciers  which  do 
not  descend  to  the  level  of  the  valley. 

"  The  largest  glacier  known  to  discharge  wholly  in  the  Yukon  basin  is 
one  which  lies  approximately  on  the  14l8t  meridan,  called  the  Klutlan, 
from  the  native  name  of  the  river  to  which  it  gives  rise.     Its  source  is  in 


* "  An  Expedition  to  the  Yukon  District,"  in  National  Geographic  Magazine,  vol.  4,  1892, 
pp.  117-162. 

'^  "Report  of  an  Expedition  to  the  Copper,  Tanana,  and  Koyukuk  Rivers,  Alaska," 
Washington,  1887,  pp.  37-43. 


106 


GLACIERS   OF   NORTH   AMERICA. 


the  great  snow  fields  between  Mount  St.  Elias  and  the  high  peaks  on  the 
northern  border  of  the  range  called  Nat-azh-at  by  the  natives.  It  extends 
several  miles  beyond  the  foot  of  the  range,  though  it  is  rapidly  recedinj,' 
at  the  present  time,  and.  is  between  four  and  five  miles  broad  where  it 
enters  the  valley.  The  stagnant  ice  in  front  of  the  retreating  glacier  is 
buried  under  a  great  accumulation  of  morainal  material  continuous  with 
the  terminal  moraine,  sc  that  it  is  impossible  to  determine  the  exact  limits 
of  the  ice.  The  heavy  mantle  of  vegetation  which  covers  the  terminal 
moraine  continues  a  mile  or  more  beyond  the  outer  edge  of  the  ice,  be- 
coming gradually  less  abundant  as  the  active  portion  of  the  glacier  is 
approached. 

"  The  moraine  in  front  of  the  Klutlan  is  the  largest  accumulated  by 
any  of  the  interior  glaciers.  It  is  composed  very  largely  of  the  white 
volcanic  tufa  already  described,  but  with  this  are  mingled  many  angular 
fragments  of  amygdaloid  lava  and  a  few  of  granite  and  gneiss.  Much  of 
the  moraine  has  been  removed  by  streams  flowing  from  the  glacier,  but 
remnant.o  200  feet  or  more  in  thickness  extend  nearly  across  to  the  high- 
land north  of  the  valley. 

"  The  second  of  the  White  River  glaciers  is  about  midway  between  the 
Klutlan  and  Scolai  pass.  It  is  much  smaller  than  the  Klutlan  and  does 
not  push  out  into  the  valley,  but  its  front  forms  a  wall  of  ice  someihiiirj 
over  a  mile  in  length  from  side  to  side  of  the  narrow  valley  in  which  it  lies. 

"  The  third  and  largest  of  the  intsrior  glaciers  flows  from  the  high  moun- 
tains northwest  of  Mount  St.  Elias  down  into  Scolai  pass,  and  from  the 
divide  sends  a  lobe  of  ice  toward  White  river  and  a  smaller  one  toward 
Copper  River  basin.  This  -vas  named  in  honor  of  Mr.  I.  C.  Russell.  The 
northern  or  White  River  lobe  of  Russell  glacier  is  buried  under  a  heavy 
accumulation  of  moraine  bearing  some  vegetation,  while  the  southern  lobe 
is  almost  wholly  free  from  morainal  material,  and  the  exposed  ice  has 
melted  down  to  the  smooth  convex  surface  and  feather  edge  characteristic 
of  stagnant  ice  at  the  front  of  a  retreating  glacier." 

Taken  altoj^jther,  the  ice  flowing  northward  from  the  St.  Elias  moun- 
tains is  insignificant  in  amount  when  compared  with  the  vast  frozen  flocid 
that  pours  down  through  every  valley,  cailon,  and  ravine  on  the  southern 
slope  of  the  same  uplift.  The  Seward  glacier  alone  probably  contains  a 
greater  volume  of  ice  than  all  the  glaciers  flowing  into  the  White  River 
basin  combined. 

Space  will  not  permit  me  to  quote  more  fully  from  Dr.  Hayes'  instructive 
description  of  the  glacier  seen  by  him,  or  to  follow  his  discussion  of  the 


GLACIERS   OF   ALASKA. 


107 


climatic  condition  on  which  the  distribution  of  the  glaciers  of  Alaska 
dejjends.  His  exp'.orations  defined  the  northern  limit  of  the  present  ice 
drainage  and  furnished  additional  information  concerning  the  extent 
inkT.d  of  the  glaciers  of  the  same  region  in  former  times. 


Absence  of  Glaciers  in  Central  and  Northern  Alaska. 

In  the  interior  of  Alaska  and  of  the  adjacent  portion  of  Canada,  there 
are  many  mountains  that  reach  elevations  of  at  least  four  or  five  thousand 
feet  above  the  sea,  but  are  bare  of  snow  during  the  summer,  and  no  glaciers 
are  known  to  exist  upon  them.  This  fact  is  the  more  striking  for  the 
reason  that  several  of  the  peaks  referred  to  are  near,  and  some  of  them 
even  north  of  the  Arctic  circle,  and  might  be  supposed  to  afford  favorable 
conditions  for  ice  accumulation.  A  good  illustration  is  thus  furnished  of 
the  conclusion  long  since  reached,  that  the  existence  of  perennial  ice  does 
not  necessarily  depend  upon  latitude.  The  snow  line  when  traced  from 
the  most  southerly  peak  in  California  that  is  snow-capped  in  summer, 
northward  along  the  Cordilleras,  becomes  lower  and  lower,  until  at  the 
base  01  Mount  St.  Elias  it  is  only  2500  feet  above  the  sea.  North  of  the 
St.  Elias  mountain  belt,  however,  it  rises  abruptly,  and  so  far  as  known  xa 
not  reached  by  any  elevations  in  the  interior. 

The  reason  for  the  apparent  anomaly  in  the  distribution  of  the  glaciers 
of  Alaska  is  to  be  found  mainly  in  the  direction  of  the  currents  of  the 
Pacific  and  in  the  topography  of  the  land.  A  warm  ocean  current, 
known  as  the  Japan  current,  corresponding  in  many  ways  with  the  Gulf 
stream,  impinges  on  the  southern  shore  of  Alaska  and  greatly  modifies 
the  condition  of  the  atmosphere.  The  warm,  humid  winds  from  the  south, 
in  passing  over  the  mountains  near  the  coast,  part  with  a  large  share  of 
their  moisture  and  descend  to  the  lower  regions  to  the  north  as  com- 
paratively dry  winds.  The  snowfall  on  the  mountains  adjacent  to  the 
coast  is  excessive,  while  in  the  interior  it  is  light.  At  elevations  ex- 
ceeding 8000  or  10,000  feet  on  the  mountains  near  the  sea  every  stcrm 
throughout  the  year  is  accompanied  with  snow,  and  above  13,000  feet, 
it  is  safe  to  say  that  rain  never  falls.  In  the  interior,  however,  not  only" 
is  a  snowstorm  in  summer  unknown,  but  rain  seldom  falls  duriiig  that, 
^season.  In  winter  the  prevailing  air  currents  of  the  interior  are  from, 
the  fix)zen  sea  to  the  northward,  and  are  in  general  dry  winds,  for  thft 
reason  that  they  travel  from  cold  to  warmer  regions  and  tend  to  absorb 
rather  than  to  precipitate  moisture.     The  mean  annual  temperature,  and 


108 


GLACIERS    OF   NOliTH    AMERICA. 


still  more  markedly  the  mean  winter  temperature  of  the  interior,  is  far 
below  what  ii  is  at  corresponding  elevations  on  the  coast,  but.  for  reasons 
already  stated,  this  is  not  necessarily  favorable  to  the  accumulation  of 
perennial  snow. 

The  glaciera  of  Alaska  illustrate  the  well-known  fact  that  the  most 
favorable,  conditions  for  ice  accumulation  are  found  where  a  region  of 
condensation  is  adjacent  to  a  region  of  active  evaporation. 

The  influence  of  climatic  and  topographic  conditions  on  the  existence 
of  glaciei-s,  just  referred  to,  is  again  strikingly  shown  in  the  far  northwest 
by  the  records  of  former  periods  of  maximum  ice  extension.  During  the 
glacial  period  the  ice  fields  adjacent  to  the  Pacific  Avere  more  extensive 
than  at  present,  but  were  confined  to  the  same  general  region.  The 
glaciers  that  flowed  northward  in  the  vicinity  of  Mount  St.  Elias  reached 
only  about  100  miles  inland.  All  of  the  central  and  northern  portions 
of  Alaska  were  unglaciated. 


Glaciers  of  the  Alaskan  Peninsula  and  the  Aleutian  Islands. 

Glaciers  of  the  alpine  type  similar  to  those  on  the  shores  of  Lynn 
canal  are  known  to  exist  in  the  mountain-enclosed  valleys  on  the  border  of 
Cook's  inlet,  and,  in  diminishing  numbers  and  decreasing  size,  from  there 
westward  on  the  Alaskan  peninsula  and  on  some  of  the  more  rugged  of 
the  Aleutian  islands.  The  positions  of  a  few  small  glaciers  on  the 
borders  of  Cook's  inlet  are  shown  on  the  charts  published  by  the  U.  S. 
Coast  and  Geodetic  Survey,  but  no  description  of  them  has  ever  been 
published.  The  verbal  reports  of  traders  and  hunters  who  have  visited 
that  region  indicate  that  the  snow  fields  crowning  the  mountains  are  ex- 
tensive and  that  the  glaciei-s  flowing  from  them  are  well  worthy  of  con- 
sideration. The  snow  line  appears  to  have  an  elevation  of  some  three  or 
four  thousand  feet,  and  the  glaciei's  are  mostly  individual  tongues  of  ice 
descending  to  within  a  few  hundred  feet  of  the  sea.  None  of  them  now 
reach  tide  water. 

The  most  extensive  of  the  isolated  snow  fields  on  the  Aleutian  islands 
yet  reported  cluster  about  the  summit  of  Mount  Makushin,  the  highest 
peak  on  Iluliuk  island.  A  view  of  that  imposing  peak  rising  white  and 
shining  above  a  most  rugged  setting  of  lesser  mountains,  obtained  by  the 
writer  from  a  commanding  summit  on  the  eastern  portion  of  the  same 
island,  showed  that  the  glaciers  on  its  sides  are  sniJill  and  similar  in  many 
ways  to  those  of  the  High  Sierra.     Their  lower  limit  appeai-s  to  be  about 


ip' 


ice         ■ 

< 

I. 

H 

5. 

uids        ■ 

X 

H 

best        H 

0 

aiul        B 
amc        H 

1 

JOUl          ■ 

4500 

mine 

islam 

know 

refere 

pectei 

peak 

tlie  if. 

graph 

extrei 

actua 


Sc 
southi 
Moun 
interv 
unite 
the  tc 
this  r 
and  I 
visite( 
to  the 
upon  : 


Ai 

unbro] 
averag 
1500  I 
state  c 
It 
its  8ur 
1500  f 
hut  is 
Its  sui 
recalls 


I.%1 


GLACIKUS   OF   ALASKA. 


109 


4500  feet  above  the  sea^  but  the  distance  rendered  it  impossible  to  deter- 
mine special  characteristics.  Some  of  the  volcanic  piles  on  the  Aleutian 
islands  to  the  west  of  Ilulink  are  higher  than  Mount  Makushin,  ^.nd  are 
known  to  be  snow-covered  in  summer ;  but  no  definite  information  in 
reference  to  the  presence  of  glaciers  on  them  is  available.  It  is  to  be  ex- 
pected that  the  great  Cordilleran  glacier  belt,  when  traced  westward  from 
peak  to  peak  on  the  Aleutian  islands,  will  rise  higher  and  higher,  and  that 
the  glacier  will  at  the  same  time  diminish  in  size,  until  at  last  the  topo- 
grftphic  and  climatic  conditions  will  preclude  their  existence.  Where  the 
extreme  western  tip  of  the  crescent  formed  by  the  Cordilleran  glacier  belt 
actually  terminates  remains  to  be  determined. 


M 


m 


Piedmont  Glaciers. 

Some  account  has  already  been  given  of  the  alpine  glaciers  on  the 
southern  slope  of  the  mountains  that  culminate  in  Mount  Logan  and 
Mount  St.  Elias.  Many  of  these  ice  streams  descend  onto  a  low  plain 
intervening  between  the  mountains  and  the  sea,  and  there  expand  and 
unite  one  with  another,  so  as  to  form  vast  lake-like  bodies  of  ice  to  which 
tlie  term  piedmont  glaciers  has  been  applied.  Two  broad  ice  sheets  of 
this  nature,  named  in  honor  of  the  distinguished  navigators  Malaspina 
and  Bering  respectively,  are  now  known,  but  only  the  former  has  been 
visited.  Bering  glacier  has  been  seen  from  vessels  passing  along  the  coast 
to  the  westward  of  Mount  St.  Elias,  but  vo  explorer  has  as  yet  set  foot 
upon  it. 

Malaspina  Glacier. 

(A  sketch  map  of  Malaspina  glacier  forms  Plate  17.) 

Area.  —  The  Malaspina  glacier,  as  indicated  on  Plate  17,  extends  with 
unbroken  continuity  from  Yakutat  bay  70  miles  westward,  and  ha^  an 
average  breadth  of  between  20  and  25  miles.  Its  area  is  approximately 
1500  square  miles,  or  intermediate  in  extent  between  the  area  of  the 
state  of  Rhode  Island  and  the  area  of  the  state  of  Delaware. 

It  is  a  vast,  nearly  horizontal  plateau  of  ice.  The  general  elevation  of 
its  surface  at  a  distance  of  five  or  six  miles  from  its  outer  border  is  about 
1500  feet.  The  central  portion  is  free  from  moraines  or  dirt  of  any  kind, 
but  is  rough  and  broken  by  thousands  and  tens  of  thousands  of  crevasses. 
Its  surface,  when  not  concealed  by  moraines,  is  broadly  undulating,  and 
recalls  the  appearance  of  the  rolling  prairie  lands  west  of  the  Mississippi. 


110 


GLACIEHS    OF   NOKTH   AMERICA. 


From  the  higher  swells  on  its  surface  one  may  see  for  many  miles  in  all 
directions  without  ohserving  a  single  object  to  break  the  monotony  of  the 
frozen  2)lain.  So  vast  is  the  glacier  that,  on  looking  down  on  it  from 
elevations  of  two  or  three  thousand  feet  above  it^  surface,  its  limits  aie 
beyond  the  reach  of  vision. 


Lobes.  —  The  glacier  consists  of  three  principal  lobes,  each  of  which  is 
practically  the  expansion  of  a  large  tributary  ice  stream.  The  largest  has 
an  eastward  flow,  toward  Yakutat  bay,  and  is  supplied  mainly  by  tlic 
Seward  glacier.  The  next  lobe  to  the  west  is  the  expanded  terminus  of 
the  Agassiz  glacier  ;  its  current  is  toward  the  southwest.  The  third  great 
lobe  lies  between  the  Chaix  and  Robinson  hills,  and  its  main  supply  of  ico 
is  from  the  Tyndall  and  Guyot  glaciers.  Its  central  current  is  southward. 
The  direction  of  flow  in  the  several  lobes  explains  the  distribution  of  the 
moraines  about  their  borders. 

The  Seward  lobe  melts  away  before  reaching  Yakutat  bay  and  ends 
with  a  low  frontal  slope,  but  its  southern  margin  has  been  eaten  into  by 
the  ocean,  so  as  to  form  the  Sitkagi  bluffs.  The  Agassiz  lobe  is  complete, 
and  is  fringed  all  about  its  outer  border  by  broad  moraines.  The  Guyot 
lobe  pushes  boldly  out  into  the  ocean,  and,  breaking  off,  forms  magnificent 
ice  cliffs. 


Characteristics   of   the    Non-moraiiie-coverecl    Surface.  —  On    the 

northern  border  of  the  glacier,  but  below  the  line  of  perpetual  snow,  where 
the  great  plateau  of  ice  has  a  gentle  sIo^jc,  the  surface  melting  givi^s 
origin  to  hundreds  of  rills  and  rivulets  which  course  along  in  channels  of 
clear  ice  until  they  meet  a  crevasse  or  moulin  and  plunge  down  into  the 
body  of  the  glacier  to  join  the  drainage  beneath.  On  warm  summer  days, 
when  the  sun  is  well  above  the  horizon,  the  mu'-mur  of  streams  may  be 
heard  wherever  the  ice  surface  is  inclined  and  not  greatly  broken  ;  but  as 
soon  as  the  shadows  of  evening  cross  the  ice  fields,  melting  ceases  and  tlie 
silence  is  unbroken.  These  streams  are  alwaj^s  of  clear,  sparkling  water, 
and  it  is  seldom  that  their  channels  contain  debris.  Where  the  surface  of 
the  glacier  is  nearly  level,  and  especially  when  broken  by  crevasses,  sur- 
face streams  are  absent,  although  the  clefts  in  the  ice  are  frequently  filled 
with  water.  The  moulins  in  which  the  larger  of  the  surface  streams 
usually  disappear  are  well-like  holes  of  great  depth.  They  are  seldom 
straight,  however,  as  the  water  in  plunging  into  them  usually  strikes  the 
opposite  side  and  causes  it  to  melt  away  more  rapidly  than  the  adjacent 


m 


CO 

<t      - 

CD       S 


a: 


a 

o 

■< 
z 

a. 
to 

•< 
_i 
•< 
2 


;3 

V 

j» 

a 
o 

00 

a> 

3 

'5 

u 


© 

09 


o   € 


z 
O 


I 


GLACIERS   OF   ALASKA. 


Ill 


surfaces.  The  water  in  descending  is  dashed  from  side  to  side  ond  in- 
cresises  their  irreguhirities,  A  deep  roar  coming  from  the  hidden  chamhei-s 
to  which  the  moulins  lead  frequently  tells  that  large  bodies  of  water  are 
rushing  along  the  ice  caves  l)eneath.  In  the  southern  portion  of  the 
glacier,  where  the  ice  has  been  deeply  melted,  and  especially  where  large 
crevasses  occur,  the  abandoned  tunnels  nmde  by  englacial  streams  are 
sometimes  revealed.  These  tunnels  are  frequently  10  or  15  feet  high, 
and  occasionally  one  may  pass  through  them  from  one  depression  in  the 
glacier  to  another.  In  «ome  instances  they  are  floored  with  debris,  some 
of  which  is  partially  rounded.  As  melting  progresses  this  material  is  con- 
centrated at  the  surface  as  a  moraine. 

The  ice  in  the  various  portions  of  the  glacier  was  observed  to  be 
formed  of  alternate  blue  and  white  bands,  as  is  the  rule  in  glacial  ice 
generally.  The  blue  bands  are  of  compact  ice,  while  the  white  bands  are 
composed  of  ice  filled  with  air  cavities.  The  banded  structure  is  usually 
nearly  vertical,  but  the  dip,  when  noticeable,  is  northward.  Nearly 
parallel  with  the  blue  and  white  layers,  but  crossing  them  at  low  angles, 
there  are  frequently  bands  of  hard,  blue  ice  several  hundred  feet  long  and 
two  or  three  inches  in  thickness  which  have  a  secondary  origin,  and  are 
due  to  the  freezing  of  waters  in  fissures. 

The  rapid  melting  of  the  surface  produces  many  curious  phenomena, 
which,  as  explained  in  a  previous  chapter,  are  common  to  many  ice  bodies 
below  the  line  of  perpetual  snow.  The  long  belts  of  stone  and  dirt  form- 
ing the  moraines  protect  the  ice  beneath  from  the  action  of  the  sun  and 
air.  while  adjacent  surfaces  waste  away.  The  result  of  this  differential 
melting  is  that  the  moraines  become  elevated  on  ridges  of  ice.  The  forms 
of  the  ridges  vary  according  to  the  amount  and  chamcter  of  the  debris 
resting  upon  them.  In  places  they  are  steep  and  narrow,  and  perhaps 
150  or  200  feet  high.  From  a  little  distance  they  look  like  solid  masses 
of  debris,  and  resemble  great  railroad  embankments,  but  on  closer  exami- 
nation they  are  seen  to  be  ridges  of  ice,  covered  with  a  thin  sheet  of  earth 
and  stones.  The  sides  of  such  ridges  are  exceedingly  difficult  to  climb, 
owing  to  the  looseness  of  the  stones,  which  slide  from  beneath  one's  feet 
and  roll  down  the  slopes.  The  larger  boulders  are  the  first  to  be  dis- 
lodged by  the  melting  of  the  ice,  and  rolling  down  the  sides  of  the 
ridges,  form  a  belt  of  coarse  debris  along  their  margins.  In  this  way  a 
marked  assortment  of  the  debris  in  reference  to  size  and  shape  frequently 
takes  place.  In  time  the  narrow  belts  of  large  bouldei-s  become  elevated  in 
their  turn  and  form  the  crests  of  secondary  ridges.     Rocks  rolling  down 


112 


ULACIEIIS   OF    NOllTli    AMEKICA. 


the  steep  .slo[)e.s  are  luoken  into  finer  and  finer  fiii(,'tnents  and  are  reduced 
in  part  to  tlie  condition  of  sand  and  clay.  When  the  dehris  is  sufliciently 
comminuted  it  is  sometimes  carried  away  hy  surfac*^  streams  and  waslied 
into  crevasses  and  mouhns.  Not  all  of  the  turbidity  of  the  suh^dacial 
streams  (!an  be  charged  to  the  grinding  of  the  glacier  over  the  rocks  on 
which  it  rests,  as  a  limited  portion  of  it  certainly  comes  from  the  crushing 
of  the  surface  moraines  during  their  frecjuent  changes  of  position. 

Isolated  blocks  of  stone  lying  on  the  glacier,  when  of  sufficient  size 
not  to  be  warmed  througli  by  the  sun's  heat  in  a  singk;  dny,  also  [jrotect 
the  ice  beneath  and  retain  their  position  as  the  adjacent  surface  melts,  so 
as  to  rest  on  pedestals  fre(iuently  several  feet  high.  These  elevated 
l)locks  are  usually  flat,  angular  masses,  sometimes  20  feet  or  more  in 
diameter.  Owing  to  the  greater  effect  of  the  sun  on  the  south<;rn  side  of 
the  columns  whicii  support  them,  the  tables  are  frequently  inclined  south- 
ward, and  ultimately  slide  off  their  pedestals  in  that  direction.  No  sooner 
has  a  block  fallen  from  its  suppoi't,  however,  than  tiic  process  is  again 
initiated,  and  it  is  again  left  in  relief  as  the  adjacent  surface  melts.  Tlie 
many  falls  which  the  larger  blocks  receive  in  this  manner  cause  them  to 
become  broken,  thus  illustrating  another , phase  of  the  process  of  comminu- 
tion to  which  surface  moraines  are  subjectf^d.  On  Malaspina  glacier  the 
formation  of  glacial  tables  is  confined  to  the  summer  season.  In  winter 
the  surface  of  the  glacier  is  snow-covered  and  differential  melting  cannot  be 
marked.  The  fact  that  glacial  tables  are  seldom  seen  just  after  the  snows 
of  winter  disappear  suggests  that  winter  melting  takes  place  to  some  extent, 
but  in  a  different  manner  from  what  it  does  in  the  summer.  Just  how  the 
blocks  are  dislodged  from  the  pedestals  in  winter  has  not  been  observed. 

While  large  objects  lying  on  the  surface  of  the  glacier  are  elevated  on 
pedestals  in  the  manner  just  described,  smaller  ones,  as  is  well  known,  and 
especially  those  of  dark  color,  become  heated  by  the  sun,  and  melting 
the  ice  beneath,  sink  into  it.  When  small  stones  and  dirt  are  gathered  in 
depressions  on  the  surface  of  the  glacier,  or  on  a  large  scale,  when 
moulins  become  filled  with  fine  debris  and  the  adjacent  surface  is  lowered 
by  melting,  the  material  thus  concentrated  acts  as  do  large  boulders,  and 
protects  the  ice  beneath.  But  as  the  gravel  rises  in  reference  to  the 
adjacent  surface,  the  outer  portion  rolls  down  from  the  pedestal  on  all 
sides,  and  the  result  is  that  a  sharp  cone  of  ice  is  formed,  having  a  sheet 
of  gravel  and  dirt  over  its  surface.  These  sand  cones,  as  they  are  called, 
sometimes  attain  a  height  of  ten  or  twelve  feet,  and  form  conspicuous  and 
cliaracteristic  features  of  the  glaciers  over  large  areas. 


r 


Si 


.J 
o 


■iBHSiiAaliiSSiMaiiiki 


GLACIKKS    OK    ALASKA. 


118 


The  Hiirface  of  Maliispina  glacier  over  many  square  miles,  where  free 
from  moraine,  w  covered  with  a  coral-like  crust,  which  results  from  the 
alternate  melting  and  frce/.ing  of  the  surfa(!e.  The  crevasses  in  this  i)or- 
tion  of  the  viust  plat»'au  are  seldom  of  large  si/.e,  and  owing  to  the  melting 
of  iheir  margins,  are  hroad  at  the  surfacie  and  contract  rapidly  downward. 
They  are  in  fact  mere  gashes,  sometimes  10  or  20  feet  deep,  and  are 
apparently  the  rcunants  of  larger  crevasses  formed  in  the  glaciei"s  which 
flow  down  from  the  mountains.  Deeper  crevasses  occur  at  certain  locali- 
ties about  the  border  of  the  glacier,  where  the  ice  at  the  margin  falls 
away  from  the  main  mass  ;  but  these  are  seldom  conspicuous,  as  the  ice  in 
the  region  where  they  occur  is  always  heavily  covered  with  debris  and  the 
openings  become  filled  with  stones  and  boulders.  The  generally  level 
surface  of  the  glacier  and  the  absence  of  large  crevasses  indicate  that  the 
ground  on  which  it  rests  is  comi)aratively  even.  Where  the  larger  of  the 
tributary  glaciers  join  it,  however,  ice  falls  occur,  caused  by  steep  descents 
in  the  ground  beneath.  These  falls  are  just  at  the  lower  limit  of  per- 
petual snow,  and  are  fully  revealed  only  when  melting  has  reached  its 
maximum  and  the  snows  of  tlie  winter  have  not  yet  begun  to  accumulate. 


F 


MornincH.  —  From  any  commanding  station  overlooking  ]Malaspina 
glacier,  one  sees  that  the  great  central  area  of  clear,  white  ice  is  bordered 
on  the  south  by  a  broad,  dark  band  formed  by  boulders  and  stones.  Out- 
side of  this  and  forming  a  belt  concentric  with  it  is  a  forest-covered  Jirea, 
in  many  places  four  or  five  miles  wide.  The  forest  grows  on  a  moraine, 
which  rests  upon  the  ice  of  the  glacier.  In  a  general  view  by  far  the 
greater  part  of  the  surface  of  the  glacier  is  seen  to  be  foraied  of  clear  ice, 
but  in  crossing  it  one  comes  firnt  to  the  forest  and  moraine-covered  border, 
Avhich,  owing  to  the  great  obstacles  it  presents  to  travel,  impresses  one  as 
being  more  extensive  than  it  is  in  reality. 

The  moraines  not  only  cover  all  of  the  outer  border  of  the  gkcier,  but 
stream  off  from  the  mountain  spurs  projecting  into  it  on  the  north.  As 
indicated  on  the  accompanying  map,  one  of  these  trains  starting  from  a 
spur  of  the  Samovar  hills  crosses  the  entire  breadth  of  the  glacier  and 
joins  the  marginal  moraine  on  its  southern  border.  This  long  train  of 
stones  and  boulders  is  really  a  highly  compound  medial  moraine  formed 
at  the  junction  of  the  expanded  extremities  of  the  Seward  and  Agassiz 
glaciers. 

All  of  the  glaciers  which  feed  the  great  piedmont  ice  sheet  are  above 
the  snow  line,  and  the  debris  they  carry  only  appears  at  the  surface  after 


114 


GLAClEllS    OF   NOKTH   AMERICA. 


the  ice  descends  to  the  region  where  the  annual  waste  is  in  excess  of  the 
annual  ipply.  The  stones  and  dirt  previously  contained  in  the  glacier 
are  then  concentrated  at  the  surface,  owing  to  the  melting  of  the  ice. 
This  is  the  history  of  all  of  the  moraines  on  the  glacier.  They  are  formed 
of  the  debris  brought  out  of  the  mountains  by  the  tributary  alpine  glaciei-s 
and  concentrated  at  the  surface  by  reason  of  the  melting  of  the  ice. 

Malaspiiia  glacier  in  retreating  has  left  irregular  hillocks  of  coarse 
debris  which  are  now  densely  ^orest-covered.  These  deposits  do  not 
form  a  continuous  terminal  moraine,  however,  but  a  series  of  irregular 
ridges  and  hills  having  a  somewhat  common  trend.  They  indicate  a  slow 
general  retreat  without  prolonged  halts.  The  heaps  of  debris  left  as  the 
ice  front  retreated  have  a  general  parallelism  with  the  present  margin  of 
the  glacier  and  are  pitted  with  lake  basins,  but  only  their  higher  portions 
are  exposed  above  the  general  sheet  of  sand  and  gravel  spread  out  by 
streams  draining  the  glacier. 

The  blocks  of  stone  forming  the  moraines  now  resting  on  the  ice  are 
of  all  sizes  up  to  20  or  30  feet  in  diameter,  but  those  of  large  dimen- 
sions are  not  common.  The  stones  are  rough  and  angular  except  when 
composed  of  material  like  granite,  which  on  weathering  forms  oval 
and  rounded  boulders  of  disintegration.  So  far  as  has  been  observed, 
very  few  of  the  stones  on  the  glacier  have  polished  or  striated  surfaces. 
The  material  of  which  the  moraines  are  composed  is  of  many  kinds,  but 
individual  r"  Iges  frequently  consist  of  fragments  of  the  same  variety 
of  rock,  the  special  kind  in  each  case  depending  on  the  source  of  the 
thi-ead  ii.  the  great  ice  current,  which  brought  the  fragments  from  the 
mountains. 

In  many  instances,  particularly  near  the  outer  border  of  the  ice  sheet, 
there  are  large  quantities  of  tenacious  clay,  filled  with  angular  stones, 
which  is  so  soft,  especially  during  heavy  rains,  that  one  may  sink  waist 
deep  in  the  treacherous  mass.  Sometimes  blocks*  of  stone  a  foot  or 
more  square  float  on  the  liquid  mud  and  lure  the  unwary  traveler  to 
disaster. 

On  the  eastern  margin  of  the  ice  sheet  adjacent  to  Yakutat  bay,  where 
the  frontal  slope  is  low.  there  are  broad  deposits  of  sand  and  well-rounded 
gravel  which  has  been  spread  out  over  the  ice.  On  the  extreme  margin 
of  the  glacier  this  deposit  merges  with  hillocks  and  irregular  knolls  of  tlio 
same  kind  of  material,  some  of  which  rise  a  hundred  feet  above  the  nearest 
exposure  of  ice  and  are  clothed  with  dense  forests.  The  debris  is  so 
abundant  and  the  ice  ends  in  such  a  low  slope  that  it  is  frequently  im- 


GLACIERS   OF   ALASKA. 


115 


possible  to  determine  where  the  glacier  actually  terminates.  The  water- 
worn  material  here  referred  to  as  resting  on  the  glacier  has  been  brought 
out  cf  tunnels  in  the  ice,  as  will  be  noticed  further  on. 


Surface  of  the  Fring-ingr  Moraines.  —  A  peculiar  and  interesting 
feature  of  the  moraine  on  the  stagnant  border  of  Mjilaspina  glacier  is 
furnished  by  the  lakelets  that  occur  everywhere  upon  it.  These  are  found 
in  great  numbers  both  in  the  forest-covered  moraine  and  in  the  outer 
border  of  the  barren  moraine.  They  are  usually  rudely  circular,  and  have 
steep  walls  of  dirty  ice  which  slope  toward  the  water  at  high  angles,  but 
are  undercut  at  the  bottom,  so  that  the  basins  in  vertical  cross-section 
have  something  of  an  hour-glass  form.  The  walls  are  frequently  from  50  to 
100  feet  high,  with  a  slope  of  40  to  50  degrees,  and  sometimes  are  nearly 
perpendicular.  Near  the  water's  edge  the  banks  ere  undercut  so  as  to  leave 
a  ri  Ige  projecting  over  the  water.  The  upper  edge  of  the  walls  is  formed 
of  the  sheet  of  debris  which  covers  the  glacier,  and  the  melting  of  the  ice 
beneath  causes  this  material  to  roll  and  slide  down  the  ice  slopes  and 
plunge  into  the  waters  below.  The  lakes  are  usually  less  than  100  feet 
in  diameter,  but  larger  ones  are  by  no  means  uncommon,  several  being  ob- 
served which  were  150  or  200  yards  across.  Their  waters  are  always 
turbid,  ovving  to  the  mud  which  is  carried  into  them  by  small  avalanches 
and  by  the  rills  that  trickle  from  their  sides.  The  rattle  of  stones  falling 
into  iliem  is  frequentlj'  heard  while  traveling  over  the  glacier,  and  is 
especially  noticeable  on  warm  days,  when  the  ice  is  melting  rapidly,  but  is 
even  more  marked  during  heavy  rains.  The  crater-like  walls  inclosing  the 
lakes  are  seldom  of  uniform  height,  but  frequently  rise  into  pinnacles. 
Between  the  pinnacles  there  are  occasionally  low  saddles,  through  which 
in  some  instances  the  lakes  overflow.  Frequently  there  are  two  low 
saddles  nearly  opposite  to  each  other,  which  suggests  that  the  lakes  were 
formed  by  the  widening  of  crevasses.  The  stones  and  dirt  which  fall  into 
them,  owing  to  the  melting  of  the  walls,  gradually  fill  their  bottoms.  In- 
stances are  numerous  where  the  waters  have  escaped  through  crevasses  or 
openings  in  the  bottom  of  the  basin,  leaving  an  exceedingly  rough  depres- 
sion, with  a  heavy  deposit  of  debris  at  the  bottom. 

As  the  general  surface  of  the  glacier  is  lowered  "by  melting,  the 
partially  filled  holes  gradually  disappear,  and  their  flooi*s,  owing  to  the 
deep  accumulation  of  debris  on  them,  which  protects  the  ice  from  melting, 
become  elevated  above  the  surrounding  surface,  in  the  same  manner  that 
glacial  tables  are  formed.     The  debris  covering  these  elevations  slides  down 


116 


GLACIEltS   OF   NORTH    AMEUICA. 


li^ 


their  sides  tos  melting  progresses  ;  and  finally  a  rugged  pyramid  of  ice, 
covered  with  a  thin  coating  of  debris,  occupies  the  place  of  the  former 
lake.  These  pyramids  frec^uently  have  a  height  of  00  or  80  feet,  and  arts 
sometimes  nearly  conical  in  shape.  They  resemble  "sand  cones,"  but  are 
of  much  greater  size  and  are  sheathed  with  coarser  debris.     The  sand  cones 


Fid.  9. —  Lakelet  ox  Malaspixa  Glaciee,  Alaska. 


are  usually,  if  not  always,  formed  and  melted  away  during  a  single 
season,  while  the  debris  pyramids  require  several  seasons  for  their  cycle 
of  change. 

Like  the  lakelets  to  which  they  owe  their  origin,  the  debris  pyramids 
are  confined  to  the  stagnant  portions  of  the  glacier  and  play  an  important 
part  in  the  breaking  up  and  comminution  of  the  material  forming  the 
marginal  moraines.  Owing  to  the  sliding  of  the  boulders  and  stones  into 
the  lakelets  and  their  subsequent  fall  from  the  sides  of  the  pyramids,  they 


GLACIKHS   OF   ALASKA. 


117 


are  broken  and  crushed,  so  tliat  the  outer  portion  of  the  glacier,  where  the 
process  has  been  going  on  longest,  is  covered  with  finer  debris  and  contains 
more  clay  and  sand  than  the  inner  portions. 

Just  how  the  holes  containing  glacial  lakelets  originate  it  is  difficult  to 
say,  but  their  formation  seems  to  be  initiated,  as  already  suggested,  by 
the  melting  back  of  the  sides  of  crevasses.  Breaks  in  the  general  sheet  of 
debris  covering  the  glacier  ex[)Ose  the  ice  beneath  to  the  action  of  the  sun 
and  rain,  which  causes  it  to  melt  and  the  crevasses  to  broaden.  The 
openings  become  purtially  filled  with  water,  and  lakelets  are  formed. 
The  waves  wash  the  debris  from  the  ice  about  the  margin  of  the  lakelets, 
thus  exposing  it  to  the  direct  attack  of  the  water,  which  melts  it  more 
rapidly  than  higher  portions  of  the  slopes  are  melted  by  the  sun  and  rain. 
It  is  in  this  manner  that  the  characteristic  hour-glass  form  of  the  basins 
origiirates.  Tlie  lakelets  are  confined  to  the  outer  or  stagnant  portion  of 
ihe  glacier,  for  the  reason  that  motion  in  the  ice  would  produce  crevasses 
through  which  the  water  would  escape.  Vv  here  glacial  lakelets  occur  in 
great  numbers  it  is  evident  that  the  ice  must  be  nearly  or  quite  stationary, 
otherwise  the  basins  could  not  exist  for  a  series  of  years.  The  lakelets 
and  the  pyramids  resultinn-  from  them  are  the  most  characteristic  features 
of  the  outer  border  of  the  glacier.  The  number  of  each  must  be  many 
thousand.  They  occur  not  only  in  the  outer  portion  of  the  barren  mo- 
raine, but  also  throughout  the  forest-covered  area  still  nearer  the  outer 
margin  of  the  glacier.  Large  quantities  of  trees  and  bushes  fall  into  them 
with  the  debris  that  slides  from  their  sides,  and  tree  trunks,  roots,  and  soil 
thus  become  buried  in  the  moraines. 


Forests  on  the  Moraines.  —  The  outer  and  consequently  older  portions 
of  the  fringing  moraines  art  covered  with  vegetation,  which  in  places,  par- 
ticularly near  the  outer  margin  of  the  belt,  has  all  the  characteristics  of 
old  forests.  It  insists  principally  of  spruce,  alder,  and  cottonwood  trees, 
and  a  great  varii  v  of  shrubs,  bushes,  and  ferns.  In  inany  places  the  ice 
beneath  the  denst  orest  is  not  less  than  a  tl.ousand  feet  thick.  The  vege- 
tiition  is  confined  principally  to  the  bordei  of  the  Seward  lobe.  Near 
Vahtse  river  the  belt  is  five  miles  broad,  but  decreases  toward  the  east  and 
is  alxsent  at  the  Sitkagi  bluffs,  where  the  glacier  is  being  eaten  away  by 
the  sea.  It  is  only  on  the  stagnant  borders  of  the  ice  sheet  that  forests 
occur.  Both  glacial  lakelets  and  forests  on  the  moraines  are  absent  where 
the  ice  has  motion.  The  forest-covered  portion  is,  by  estimate,  l)etween 
-0  and  25  square  miles  in  area. 


118 


GLACIERS   OF   NORTH    AMERICA. 


I 

PI 


Character  of  the  Outer  .^Inr^-in. — The  soutliern  margin  of  Malaspinu 
glacier,  between  the  Yahtse  and  Point  Manl)y,  is  al)rn|)t,  and  forms  a 
bluff  that  varies  in  height  from  140  to  300  feet  or  more.  The  bluff  is 
so  steep  in  most  places  and  is  so  heavily  encuml)ered  with  fallen  trees 
and  boulders  that  it  is  with  difficulty  one  can  climb  it.  Often  the 
trouble  in  ascending  is  increased  by  landslides,  Avhich  have  piled  the 
superficial  r.iaterial  in  confused  heaps,  and  in  other  instances  the  melting 
of  tiie  ice  beneath  the  vegetation  has  left  concealed  pitfalls  into  which 
one  may  drop  without  warning.  The  bluff  formed  by  the  margin  of  the 
glacier,  when  not  washed  by  the  sea,  is  boldest  and  steepest  where  the 
covering  of  vegetation  is  most  dense.  Where  the  covering  consists  of 
stones  and  dirt  without  vegetation,  however,  the  margin  may  still  be 
bold.  This  is  illustrated  between  the  mouth  of  the  Yahtee  and  Icy  cape, 
where  the  ice  is  concealed  beneath  a  general  sheet  of  debris,  but  has  a 
bold  convex  margin  which  rises  abruptly  from  the  desolate,  torrent-swept 
waste  at  its  base. 

When  the  glacier  meets  the  sea  the  ice  is  cut  away  at  the  water-level, 
and  blocks  fall  from  above,  leaving  perpendicular  cliffs  of  clear  ice.  At 
Icy  cape  there  is  a  bold  headland'  of  this  nature  from  which  bergs  are 
continuall}^  falling  with  a  thunderous  roar  that  may  be  heard  fully  twenty 
miles  away.  On  the  crest  of  the  cliffs  of  clear  blue  ice  there  is  a  dark 
band  formed  by  the  edge  of  the  sheet  of  debris  covering  the  glacier,  and 
showing  that  the  moraine  which  blackens  its  surface  along  its  outer 
margin  is  entirely  superficial.  At  Sitkagi  bluffs  the  glacier  is  again 
washed  by  the  sea,  but  the  base  of  the  ice  is  there  just  above  the  water- 
level  and  recession  is  slow.  The  bluffs  are  heavily  covered  with  stones 
and  dirt,  and  icebergs  do  not  form. 

At  the  heads  of  the  gorges  in  the  margin  of  the  glacier  leading  to  the 
mouths  of  tunnels,  the  dirt-covered  ice  forms  bold  cliffs  which  are  most 
precipitous  at  the  heads  of  the  reentrant  angles.  The  eastern  margin  rt 
the  icf,  sheet  facing  Yakutat  bay  is  low,  and  covered  to  a  large  extent 
with  water-worn  debris.  The  ridges  on  the  glacier  formed  by  moraines 
are  there  at  right  angles  to  the  margin  of  the  ice,  and  are  bare  of  vege- 
tation. The  reason  for  the  exceptionally  lo\v  slope  of  the  eastern  margin 
of  the  ice  sheet  seems  to  be  that  the  current  jn  the  ice  is  there  eastward, 
and  the  glacier  is  melting  back  without  leaving  a  stagnant  border.   : 


Marginal    Lakes.  —  The  water  bodies    here    referred    to   are    called 
marflinal  lakes,  for  the  reason  that  they  are  peculiar  to  the  margins  of 


« 


X 

u 


."3 

to 

LU 

X 


O 


CO 


o 

z 

o 
o 


it: 

CO 


cc 

LU 

(3 

<t 
_l 

o 
z 

CL 
CO 

•< 


i 


glaci 

beeo] 

the  a 

marg 

tliroi 

a  lies 

.spur 

and  : 

watei 

lakes 

Hitcl 

y 

ice  01 
the  c 
lakes 
they 
throu 

A 
the  d 
find  ( 
a  sub 
the  ti 
obstrt 
on  th 
the  I 
Switz 

O 
might 
far  ol 
forma 
lakes 
Wher 
strati  1 
lakes 
are  ir 
Malas 
may  c 

D: 
nunat 


GLACIERS    OF   ALASKA. 


119 


glaciers.  Where  rocks  border  an  ice  field  or  project  through  it  they 
become  heated,  especially  on  southern  exposures,  and,  radiating  heat  to 
the  adjacent  ice,  cause  it  to  melt.  A  depression  is  thus  formed  along  tlie 
margin  of  the  ice  which  becomes  a  line  of  drainage.  Water  flowing 
through  such  a  channel  accelerates  the  melting  of  the  ice,  at  least  until 
a  heavy  coating  of  debris  has  accumulated.  When  a  steep  mountain 
spur  projects  into  an  ice  field,  the  lines  of  drainage  on  each  side  converge 
and  frequently  unite  at  its  extremity,  forming  a  lake,  from  which  the 
water  usually  escapes  through  a  tunnel  in  the  ice.  Typical  instances  of 
lakes  of  this  character  occur  at  Terrace  point,  at  the  south  end  of  the 
Hitchcock  range,  and  again  about  the  base  of  the  Chaix  hills. 

When  a  stream  flows  along  the  side  of  a  glacier  a  movement  in  tlie 
ice  or  the  sliding  of  stones  and  dirt  from  its  surface  sometimes  obstructs 
the  drainage  and  causes  the  formation  of  another  variety  of  marginal 
lakes.  In  such  instances  the  imprisoned  waters  usually  rise  until 
they  can  find  an  outlet  across  the  barrier,  and  then  cut  a  channel 
through  it. 

A  glacier  in  flowing  past  the  base  of  a  mountain  frequently  obstructs 
the  drainage  of  lateral  valleys,  and  causes  lakes  to  form.  These  usually 
find  outlets,  as  in  the  case  of  lakes  at  the  end  of  mountain  spurs,  through 
a  subglacial  or  englacial  tunnel,  and  are  filled  or  emptied  according  as 
the  tunnel  through  which  the  watei"s  escape  affords  free  drainage,  or  is 
obstructed.  Several  examples  of  this  variety  of  marginal  lakes  occur 
on  the  west  and  south  sides  of  the  Chaix  hills.  They  correspond  in 
the  mode  of  their  formation  with  the  well-known  Merjelen  lake  of 
Switzerland. 

Other  variations  in  the  manner  in  which  glaciers  obstruct  drainage 
might  be  enumerated,  but  those  mentioned  cover  all  of  the  examples  thus 
far  observed  about  Malaspina  glacier.  The  conditions  which  lead  to  the 
formation  of  the  marginal  lakes  are  unstable,  and  the  records  which  the 
lakes  leave  in  the  form  of  terraces,  deltas,  etc.,  are  consequentl}  irregular. 
When  streams  flow  into  one  of  these  lakes,  deltas  and  horizontally 
stratified  lake  beds  are  formed  as  in  ordinary  water  bodies  ;  but,  as  the 
lakes  are  subject  to  many  fluctuations,  the  elevations  at  which  the  records 
are  made  are  continually  changing,  and  in  instances  like  those  about 
Malaspina  glacier,  where  the  retaining  ice  body  is  constantly  diminishing, 
may  occupy  a  wide  vertical  interval. 

Drainage  begins  on  the  southeast  side  of  Chaix  hills  at  Moore's 
nunatak,  where,  during  the  time  of  our  visit,  there  were  two  small  lakes, 


1^0 


GLACIERS    OF   NORTH    AMERICA. 


walled  in  on  nearly  all  sides  by  the  moraine-covered  ice  of  Malaspinu 
glacier.  The  water  filling  these  basins  comes  principally  from  the  high 
ice  fall  at  the  north,  where  the  glacier  descends  over  a  projecting  spur 
running  east  from  Moore's  nunatak.  The  water  escaped  from  the  first 
lake  across  a  confused  mass  of  debris  which  had  slid  from  the  ice  bluff 
bordering  the  stream^  and  formed  a  temporary  dam.  Below  the  dam  the 
water  soon  disap[)eared  beneath  deeply  crevassed  and  heavily  moraine- 
covered  ice,  and  came  to  light  once  more  at  the  mouth  of  a  tunnel  nbout 
a  mile  to  the  southwest.  The  second  lake,  at  the  time  of  our  visit,  had 
almost  disappeared,  but  its  former  extent  was  plainly  marked  by  a  barren 
sand-flat,  many  acres  in  extent,  and  by  terraces  along  its  western  border. 
The  lake  occupied  a  small  embayment  in  the  hills,  tlie  outlet  of  which 
had  been  closed  by  the  ice  flowing  past  it.  Below  the  second  lake  the 
stream  flows  along  the  base  of  densely  wooded  knolls,  and  has  a  steep, 
moraine-covered  bluff  of  ice  for  its  left  bank.  About  a  mile  below,  it 
turns  a  sharp  projection  of  rocks  and  cuts  deeply  into  its  left  bank,  which 
stands  {is  an  overhanging  bluff  of  dirty  ice,  over  100  feet  high.  The 
stream  then  flows  nearly  due  west  for  some  three  miles  to  Crater  lake.  On 
its  right  bank  is  a  terrace  about  150  feet  high,  which  skirts  the  base  of 
the  Chaix  hills,  and  marks  the  position  of  the  stream  at  a  former  stage. 
The  terrace  is  about  100  yards  broad,  and  above  it  are  two  other  terraces 
on  the  mountain  slope,  one  at  an  elevati  >*\  of  50  feet,  and  the  other  at 
75  feet,  above  the  broad  terrace-  The  upper  terraces  were  only  observed 
at  one  locality,  and  were  probably  due  to  deposits  formed  in  a  margiiud 
lake  at  the  end  of  a  mountain  spur. 

The  terraces  left  by  streams  flowing  between  a  moraine-covered  glacier 
and  a  precipitous  mountain  slope  are  peculiar  and  readily  distinguishable 
from  other  similar  topographic  features.  The  channels  become  filled 
principally  with  debris  which  slides  down  the  bank  of  ice.  This  material 
is  angular  and  unassorted,  but  when  it  is  brought  within  the  reach  of 
flowing  waters  soon  becomes  rounded  and  worn.  On  the  margin  of  the 
channel,  adjacen*"  to  the  glacier,  there  is  usually  a  heavy  deposit  of  unas- 
sorted debris,  which  rests  partly  upon  the  ice  and  forms  the  actual  border 
of  the  stream.  When  the  glacier  is  lowered  by  melting,  the  stream 
abandons  its  former  channel  and  repeats  the  process  of  terrace-building  at 
a  lower  level.  The  material  forming  the  terrace  at  the  base  of  Chaix 
hills  is  largely  composed  of  blue  clay  filled  with  both  angular  and  rounded 
stones  and  boulders,  but  its  elevated  bqrder  is  almost  entirely  of  angular 
debris.     The  drainage   from  the   mountain   slope   above   the  terrace   is 


GLACIERS    OF   ALASKA. 


121 


obstructed  by  the  elevated  border  referred  to,  and  swamps  and  lagoons 
have  formed  back  of  it.  In  the  material  forming  the  terraces  there  are 
many  tree  trunks,  and  growing  upon  its  surface  there  is  a  forest  of  large 
spruce  trees. 

At  the  extreme  southern  end  of  the  Chaix  hills  the  drainage  from  the 
northeast,  which  we  have  been  tracing,  joins  another  sti'eam  from  the 
northwest  and  forms  Lake  Castani.  This  lake,  like  the  one  at  Terrace 
point,  is  at  the  south  end  of  a  precipitous  mountain  ridge  projecting  into 
the  glacier,  and  drains  through  a  tunnel  in  the  ice.  The  stream  flowing 
from  it  is  known  as  the  Yahtse,  and  flows  for  six  or  eight  miles  beneath 
the  ice  before  emerging  at  its  southeril  margin.  Large  quantities  of  both 
coaree  and  fine  material  are  being  carried  into  Lake  Castani  by  tributary 
streams,  and  are  there  deposited  as  deltas  and  lake  beds.  When  the  lake 
is  drained,  as  sometimes  happens,  vast  quantities  of  this  material  must  be 
carried  into  the  tunnel  through  which  the  waters  escape. 

On  the  west  side  of  Chaix  hills  are  several  other  marginal  lakes  of  the 
same  general  character  as  those  just  described.  The  one  next  northwest 
of  Lake  Castani  occupies  a  long,  narrow  valley  between  two  outstanding 
mountain  ridges,  and  is  retained  by  the  glacier  which  blocks  the  end  of 
the  recess  thus  formed.  This  lake  was  clear  of  ice  July,  1891,  and  of  a 
dark  blue  color,  showing  that  it  received  little  drainage  from  the  glacier. 
Other  lakes  on  the  northwest  side  of  the  Chaix  hills  are  of  a  similar 
nature,  and  during  my  visit  were  heavily  blocked  with  floating  ice.  On 
the  north  side  of  Chaix  hills  there  are  other  small  water  bodies  occupying 
embayments,  and  retained  by  the  glacier  which  flows  past  their  entrances. 
The  water  from  all  these  lakes  escapes  through  tunnels. 

The  lakes  to  which  attention  has  been  directed  are  especially  interest- 
ing, as  they  illustrate  one  phase  of  deposition  depending  upon  glaciation, 
and  suggest  that  a  great  ice  sheet  like  that  which  formerly  covered  New 
England  very  likely  gave  origin  to  marginal  lakes,  the  records  of  which 
should  be  found  on  steep  mountain  slopes. 


Drainage.  —  The  drainage  of  the  Malaspina  glacier  is  essentially 
englacial  or  subglacial.  There  is  no  surface  drainage  excepting  in  a  few 
localities,  principally  on  its  northern  border,  where  there  is  a  slight  sur- 
ffice  slope,  but  even  in  such  places  the  streams  are  short  and  soon  plunge 
into  a  crevasse  or  a  moulin  and  join  the  drainage  beneath. 

On  the  lower  portions  of  the  alpine  glaciers,  tributary  to  the  ma'  ■..  ice 
sheet,  there  are  sometimes  small  streams  coursing  along  in  ice  channels, 


122 


OLACIEU8    OF   NORTH    AMKRICA. 


but  these  are  short-lived.  On  the  borders  of  the  tributary  glaciers  then; 
are  fre([uently  important  streams  flowiupf  between  the  iee  and  the  adjacent 
mountain  slope,  but  when  these  come  down  to  the  Malaspina  glacier  they 
flow  into  tunnels  and  are  lost  to  view. 

Along  the  southern  margin  of  the  glacier,  between  the  Yahtse  and 
Point  Manby,  there  are  hundreds  of  streams  which  pour  out  of  the  escarp- 
ment formed  by  the  border  of  the  glacier,  or  rise  like  great  fountains  from 
the  gravel  and  bouldei's  accumulated  at  its  base.  All  of  these  are  brown 
and  heavy  with  sediment  and  overloaded  with  boulders  and  stones.  The 
largest  and  most  remarkable  of  these  springs  is  the  one  indicated  on  the 
accompanying  map  as  Fountain  'stream.  This  comes  to  the  surface; 
through  a  rudely  circular  opening,  nearly  100  feet  in  diameter,  surrounded 
in  part  by  ice.  Owing  to  the  pressure  to  which  the  waters  are  subjected, 
they  boil  up  violently,  and  are  thrown  into  the  air  to  the  height  of  12  or 
15  feet,  and  send  jets  of  spray  several  feet  higher.  The  waters  are  brown 
with  sediment,  and  rush  seaward  with  great  rapidity,  forming  a  roaring 
stream  fully  200  feet  broad,  which  soon  divides  into  many  branches,  and 
is  spreading  a  sheet  of  gravel  and  sand  right  and  left  into  the  adjacent 
forest.  Where  Fountain  stream  rises  (  Face  of  the  glacier  is  steep  and 
covered  with  huge  boulders,  many  of  which  are  too  large  for  the  wateis 
to  move.  The  finer  material  has  been  waslied  away,  however,  and  a 
slight  recession  in  the  face  of  the  ice  bluff  has  resulted.  The  largest 
stream  draining  the  glacier  is  the  Yahtse.  This  river,  as  already  stated, 
rises  in  two  principal  branches  at  the  base  of  the  Chaix  hills,  and  flowing 
through  a  tunnel  some  six  or  eight  miles  long,  emerges  at  the  border  of 
the  glacier  as  a  swift  brown  flood  fully  100  feet  across  and  15  or  20  feet 
deep.  The  stream^  after  its  subglacial  course,  spreads  out  into  many 
branches,  and  is  building  up  an  alluvial  fan  which  has  invaded  and  buried 
several  hundred  acres  of  forest. 

In  traversing  the  coast  from  the  YahtSe  to  Yakutat  bay,  we  crossed  a 
large  number  of  streams  which  drain  the  ice  fields  of  the  north,  some  of 
which  were  large  enough  to  be  classed  as  rivers.  When  the  streams,  on 
flowing  away  from  the  glacier,  are  large,  they  divide  into  many  branches, 
as  do  the  Yahtse  and  Fountain,  and  enter  the  sea  by  several  mouths. 
When  the  streams  are  small,  however,  they  usually  unite  to  form  large 
rivers  before  entering  the  ocean.  The  Yahtse  and  Fountain,  as  we  have 
seen,  are  examples  of  the  first,  while  Manby  and  Yahna  streams  are 
examples  of  the  second  class.  Manby  stream  rises  in  hundreds  of  small 
springs  along  the  margin  of  the  glacier,  which  flow  across  a  desolate, 


aHM 


GLACIKUS   OF   ALASKA. 


128 


torrent-swept  area,  and  unite  just  before  reaching  the  ocean  into  one 
broad,  swift  flood  of  muddy  water,  much  too  dee])  for  one  to  wade. 

On  the  border  of  the  ghicier  facing  Yakutat  Iwy,  however,  the  <hain- 
age  is  different.  The  flow  of  the  ice  is  there  eastward,  although  the 
iiiargiki  is  probably  stagnant,  and  instead  of  forming  a  bold,  (Mintinuous 
escarpment,  ends  irregularly  and  with  a  low  frontal  slope.  The  principal 
streams  on  the  eastern  margin  in  1891,  were  the  Osar,  Kame,  an»l  Kwik. 
l"^ach  of  these  issues  from  a  tunnel  and  flows  for  some  distance  between 
walls  of  ice.  Of  the  three  streams  mentioned,  the  most  inteicsting  is  the 
Kame,  which  issues  as  a  swift  brown  flood  partially  choked  with  broken 
ice  from  the  mouth  of  a  tunnel,  and  flows  for  half  a  mile  in  an  oj)en  cut 
between  precipitous  walls  of  dirty  ice  80  to  100  feet  high.  I'his  is  the 
longest  open  drainage  channel  that  I  have  yet  seen  in  the  ice.  It  is  about 
50  feet  broad  where  the  stream  rushes  from  the  glacier,  but  soon  widens 
to  several  times  this  breadth.  Its  bottom  is  covered  with  rounded  gravel 
and  sand,  and  along  its  sides  are  sand-flats  and  terraces  of  gravel  resting 
upon  ice.  The  swift,  muddy  current  was  dotted  with  small  bergs  stranded 
here  and  there  in  the  center  of  the  stream,  showing  that  the  water  was 
shallow.  Evidently  the  stream  has  a  long  subglacial  course,  and  carries 
with  it  large  quantities  of  stones,  which  are  rounded  as  in  ordinary  rivers. 
Gravel  and  sand  are  being  rapidly  deposited  in  the  ice  channel  through 
which  it  flows  after  emerging  from  its  tunnel.  Broad  sand-flats  aie  being 
spread  out  in  the  lakes  and  swamps  two  or  three  miles  to  the  east.  The 
stream  is  some  four  or  five  miles  in  length,  and  near  Yakutat  bay 
meanders  over  a  barren  area  perhaps  a  mile  broad.  I  have  called  it  Kame 
stream  because  of  a  ridge  of  gravel  running  parallel  with  it,  which  Avas 
deposited  during  a  former  stage,  when  the  waters  flowed  al)()ut  100  feet 
higher  than  now  and  built  up  a  long  ridge  of  gravel  on  the  ice  which 
has  all  the  characteristics  of  the  kames  in  New  England.  In  the  more 
definite  classification  of  glacial  sediments  now  adopted,  this  would  more 
properly  be  called  an  osar. 

Near  the  shore  of  Yakutat  bay,  the  streams  from  the  glacier  spread 
out  in  lagoons  and  sand-flats,  where  much  of  the  finer  portion  of  the 
material  they  carry  is  deposited.  Sometimes  this  debris  is  sj^read  out 
above  the  ice,  and  forms  level  terraces  of  fine  sand  and  mud  which  Ijecome 
prominent  as  the  glacier  wastes  away. 


Osars.  —  The  drainage  of  tb^  glacier  has   not 'been  investigated  as 
fully  as  its  importance  demands,  but  the  observations  already  made  seem 


124 


OLACIEKS   OF    NOICTII    AMEIIICA. 


jass. 

to  warrant  certain  conclusions  in  reference  to  deposits  made  within  the 
ghicier  by  suhghicial  or  engUuiial  streams. 

When  the  streams  from  tlie  north  reach  the  glacier  they  invariably 
flow  into  tunnels  and  disappear  from  view.  The  entrances  to  the  tunnels 
are  frecpiently  high  arches,  and  the  streams  flowing  into  them  carry  along 
great  cjuantities  of  gravel  and  sand.  About  the  southern  and  eastern 
borders  of  the  glacier,  where  the  streams  emerge,  the  arches  of  the  tunnels 
are  low,  owing  i)rinci[)ally  to  the  accumul'Uion  of  debris  which  obstructs 
their  discharge.  In  some  instances,  as  at  tiie  head  of  Fountain  streanj, 
the  accumulation  of  debris  is  so  great  that  the  water  rises  through  a 
vertical  shaft  in  order  to  reach  the  surface,  and  rushes  upward  under 
great  pressure.  The  streams  flowing  from  the  glacier  bring  out  large 
(juantities  of  well-rounded  sand  and  gravel,  much  of  which  is  immediately 
deposited  in  alluvial  cones.  This  much  of  the  work  of  subglacial  streams 
is  open  to  view,  and  enables  one  to  infer  what  takes  place  within  the 
tunnels,  and  tr>  analyze,  to  some  extent,  the  processes  of  stream  depo- 
sition beneath  gbaciai  ic? 

The  streams  issuing  from  the  ice  are  overloaded,  and  besides,  on 
emerging,  frequently  receive  large  quantities  of  coarse  debris  from  the 
adjacent  moraine-covered  ice  cliffs.  The  streams  at  once  deposit  the 
coarser  portion  of  their  loads,  thus  building  up  their  channels  and  obstruct- 
ijig  the  outlets  of  the  tunnels.  The  blocking  of  the  tunnels  must  cause 
the  subglacial  streams  to  lose  force  and  deposit  sand  and  gravel  on  the 
bottom  of  their  channels  ;  this  causes  the  water  to  flow  at  higher  levels, 
and,  coming  in  contact  with  the  roofs  of  the  tunnels,  enlarges  them 
upwards  ;  this  in  turn  gives  room  for  additional  deposits  within  the  ice 
as  the  alluvial  cones  at  the  extremities  of  the  tunnels  grow  in  height" 
In  this  way  narrow  ridges  of  gravel  and  sand,  having,  perhaps,  some 
stratification  due  to  periodic  variations  in  the  volume  of  the  streams,  may 
be  formed  within  the  ice.  When  the  glacier  melts,  the  gravel  ridges  con- 
tained within  it  will  be  exposed  at  the  surface,  and  as  the  supporting  walls 
melt  away,  the  gravel  at  the  top  of  the  ridge  will  tend  to  slide  down  so 
as  to  give  the  deposit  a  pseudo-anticlinal  structure.  Ridges  of  gravel 
deposited  in  tunnels  beneath  the  moraine-covered  portion  of  the  ISJalaspina 
glacier  would  have  boulders  dropped  upon  them  as  the  ice  melts,  but 
where  the  glacier  is  free  from  surface  debris  there  would  be  no  angular 
material  left  upon  the  ridges  when  the  ice  finally  disappeared.  Such  a 
system  of  deposition  as  is  sketched  above  would  residt  in  the  formation 
of  narrow,  winding  ridges  of  cross-bedded  sand  and  gravel,  corresponding. 


m 


riLArir.HH  OK  North  Amkkk  a. 


P1.ATIC  21. 


Fig,   a.  — moraine-covered    BORDER    OF    MALASPINA    GLACIER,    FROM 

BLOSSOM    ISLAND. 

(Dniwii  lri>iii  a  I'liotonriiph.) 


Fig.    B.  — ENTRANCE   TO    TUNNEL    IN    MALASPINA   GLACIER. 
CDrawn  from  a  Photograph.) 


"M 


i 


seemi 
proce; 
of  th€ 
it  is  e 
mighl 

A 

Malas 

sand, 

deposi 

comm 

the  " 

portio 

not  be 

cones. 

As 

]\Ialas 

stones 

and  d( 

in  this 

of  a  ti 

coarse 

region 

beneat 

alluvia 

of  the 

retreat 

course! 

as  the 

which 

is  mor( 

the  de 

probab 

trunks 

alluvia 

way  til 

of  one 

at  the 

outer  1 


»nwj«wi 


GLACIKUS    OF    ALASKA. 


125 


seemingly,  in  every  way  to  the  osars  of  many  glaciated  regions.  The 
process  of  suhglacial  deposition  pertains  especially  to  stagnant  ice  sheets 
of  the  Malaspina  type,  which  are  wasting  away.  In  an  advancing  glacier 
it  is  evident  that  the  conditions  would  be  different,  and  sul)glacial  erosion 
might  take  place  instead  of  suhglacial  deposition. 


Alluvial  Cones.  —  Below  the  outlets  of  the  tunnels  through  which 
Malaspina  glacier  is  drained,  there  are  immense  deposits  of  boulders,  gravel, 
sand,  and  mud  which  have  the  form  of  segments  of  low  cones.  These 
deposits  are  of  the  nature  of  the  "alluvial  cones"  or  "alluvial  fans"  so 
common  at  the  bases  of  mountains  in  arid  regions,  and  are  also  related  to 
the  "cones  of  dejection,"  deposited  by  torrents,  and  to  the  subaerial 
portion  of  the  deltas  of  swift  strcrms.  As  deposits  of  this  nature  have 
not  been  satisfactorily  classified,  I  shall,  for  the  present,  call  them  "  alluvial 
cones." 

As  stated  in  speaking  of  osars,  the  streams  issuing  from  tunnels  in 
Malaspina  glacier  at  once  begin  to  deposit.  The  larger  bouldera  and 
stones  are  first  dropped,  while  gravel,  sand,  and  silt  are  carried  farther 
and  deposited  in  the  order  of  their  coarseness.  The  deposits  originating 
in  this  way  have  a  conical  form,  the  apex  of  each  cone  being  at  the  mouth 
of  a  tunnel.  As  the  apexes  of  the  cones  are  raised  by  the  deposition  of 
coarse  material,  their  peripheries  expand  in  all  directions,  and,  as  the 
region  is  densely  forest-covered,  great  quantities  of  trees  beoorae  buried 
beneath  them.  As  the  ice  at  the  head  of  an  alluvial  cone  recedes,  the 
alluvial  deposit  follows  it  by  deposition  on  the  .ip-stream  side.  The  growth 
of  the  alluvial  cones  will  continue  so  long  as  the  glacier  continues  to 
retreat,  or  until  the  streams  vrhich  flow  over  them  have  their  suhglacial 
courses  changed.  The  material  of  the  alluvial  cones  is  as  heterogeneous 
as  the  material  forming  the  moraines  on  the  border  of  the  glacier  about 
which  they  form,  but  the  greater,  and  practically  the  entire,  accumulation 
is  more  or  less  rounded  and  waterworn.  Cross  stratification  characterizes 
the  deposits  throughout,  and  on  the  surface  of  many  of  the  cones  and 
probably  in  their  interior,  also,  there  are  large  quantities  of  broken  tree 
tiimks  and  branches.  The  coarse  deposits  first  laid  down  on  a  growing 
alhivial  cone  are  buried  beneath  later  deposits  of  finer  material  in  such  a 
way  that  a  somewhat  regular  stratification  may  result.  A  deep  section 
<it'  one  of  these  deposits  should  show  a  gradual  change  from  fine  material 
at  the  top  to  coarse  stones  and  subangular  ^ouldei-s  at  the  bottom.  Their 
outer  borders  are  of  fine  sand  and  mud,  and  when  the  distance  of  the 


I  UViipi  W  Wi| 


120 


GLACIERS   OF   NORTH    AMERICA. 


ocean  is  sufficient,  the  streams  flowing  from  them  deposit  large  quantities 
of  silt  on  their  flood  plains.  The  very  finest  of  the  glacial  mud  is 
delivered  to  the  ocean  and  discolors  its  water  for  many  miles  from  land. 
The  formation  of  alluvial  cones  about  the  border  of  a  stagnant  kc, 
sheet  and  the  deposition  of  ridges  of  gravel  within  it,  have  an  intimati; 
connection,  and  are,  in  fact,  but  phases  of  a  single  process.  The  growth 
of  an  alluvial  cone  tends  to  obstruct  the  mouth  of  the  tunnel  through 
which  its  feeding  stream  dischar[;es  ;  this  causes  the  stream  to  deposit 
within  the  tunnel  ;  this  again  raises  the  stream  and  allows  it  to  build  its 
alluvial  cone  still  higher.  In  the  case  of  Malasi)ina  glacier,  where  this 
process ^as  been  observed,  the  ice  sheet  is  stagnant,  at  least  on  its  border, 
and  is  retreating.  The  ground  on  which  it  rests  is  low,  but  is  thought  to 
be  slightly  higher  en  the  southern  margin  of  the  glacier  than  under  its 
central  portion.  The  best  development  of  alluvial  cones  and  osars  would 
be  expected  in  a  stac,'nant  ice  sheet  resting  on  a  gently  inclined  surface, 
with  high  lands  on  tJie  upper  border  from  whi^;h  abundant  debris  could 
be  derived.  These  ideal  conditions  are  nearly  reached  in  the  example 
described. 

Glacial  aiitl  Ocean  Records.  —  Much  has  been  written  concerning 
the  clifiracter  of  the  deposits  made  ^)y  glaciers  wdcu  they  meet  the  ocean, 
but  so  far  as  can  be  judged  from  the  conditions  observed  about  the  bordeis 
of  Malaspina  ice  sheet,  the  sea  is  mucii  more  powerful  than  the  ice. 
Where  the  two  unite  their  action,  the  sta  leaves  the  more  conspicuous 
records.  The  waters  are  active  and  aggressive,  while  the  glacier  is 
passive.  Where  the  glacier  enters  the  ocean  its  records  are  at  once 
modified  and  to  a  great  extent  obliterated.  The  presence  of  large  boulders 
in  marine  sediments  or  in  gravels  and  sands  along  the  coast  's  about  all 
the  evidence  of  glacial  uction  that  can  be  expected  under  the  conditions 
referred  to.  Where  the  swift  streams  from  the  Malaspina  glacier  enter 
the  ocean,  the  supremacy  of  the  waves,  tided,  and  currents  is  even  more 
marked.  The  streams' are  immediately  turned  aside  by  the  accumulation 
of  sandbars  across  their  mouths,  and  notliing  of  the  nature  of  stream-worn 
channels  beneath  the  level  of  the  ocean  can  exist.  All  of  the  deposits 
along  the  immediate  shore  between  the  Yahtse  and  Yakutat  bay  have  the 
characteristic  topogrtiphic  features  resulting  from  the  action  of  waves  and 
currents,  and  do  not  even  suggest  the  proximity  of  a  great  glacier. 

Recent  Advance.  —  On  the  eastern  margin  of  Malaspina  glacier, 
about  four  miles  north  of  Point  Manby,  there  is  a  locality  where  the  ice 


GLACIEUS    OF    ALASKA. 


127 


lias  recently  advanced  into  the  dense  forest  and  cut  scores  of  great  spruce 
trees  short  off  and  piled  them  in  confused  heaps.  After  this  advance  the 
ice  retreated,  leaving  the  surface  strewn  with  irregular  heajjs  of  houlders 
and  stones,  and  enclosing  many  basnis,  which,  at  the  time  of  our  visit,  were 
full  of  water  to  the  brim.  The  glacier,  during  its  advance,  ploughed  up 
a  ridge  of  blue  clay  in  front  of  it,  thus  revealing,  in  a  very  satisfactory 
manner,  the  character  of  the  strata  on  which  it  rests.  The  clay  is  thickly 
charged  with  sea-shells  of  living  species,  proving  that  the  glacier,  during 
its  former  great  advance,  probably  extended  to  the  ocean,  and  that  a  rise 
of  the  land  lias  subsecjuentlj'  occurred.  This  is  in  harmony  with  many 
other  observations  which  show  that  the  coast  adjacent  to  Malaspina 
glacier  is  now  rising.  The  blue  color  of  the  subglacial  strata  is  in  marked 
c<:ntrast  with  the  browns  and  yellows  of  the  moraines  left  on  its  surface 
hy  the  retreati'ig  ice,  which,  in  common  with  the  fringing  moraines  still 
resting  on  the  glacier,  show  considerable  weatheriu'^,  Among  the  shells 
collected   in  the  subglacial   clay,    Dr.    W.    H.    Dall  has  identified   the 

following :  ' 

Cardium  aronlaniUcnm.  Gronl. 
Cardium  islandieum,  L. 
Kennerlia  (/randis^  Dall. 
Leda  fossa.  Baird. 
Macoma  sahulosa,  Spengler. 

Similar  shells,  all  of  living  species,  were  previously  found  at  an 
elevation  of  5000  feet  on  the  crest  of  a  fault  scarp  at  Pinnacle  pass, 
pillowing  that  recent  elevations  of  land,  much  greater  than  the  one 
recorded  in  the  marine  clay  just  noticed,  have  taken  place.  In  fact  there 
iue  several  indications  that  the  coast  in  the  vicinity  has  been  rising,  and 
that  the  same  process  is  still  continuing. 


if 


Subsoil  Ice.i 

On  several  occasions  while  traveling  in  central  and  northern  Alaska, 
I  fonnd,  by  removing  a  few  inches  of  the  moss  which  generally  covers 
the  ground,  that  the  subsoil  was  solidly  frozen.  This  occurrence  was 
especially  striking  on  summer  days  Avhen  the  (empj^ratnre  of  the  air  in 
the  shade  was  frequently  l)etween  90°  aiul  100°  of  the  Fahrenheit  scale. 

'  Observations  on  tlie  subsoil  ioe  of  Alaska  by  the  present  vvriler,  logether  with  referencea 
to  a  number  of  previously  publislied  papers  oii  the  same  subject,  may  be  found  in  tlie  Bulletl'i 
of  the  Geological  Society  of  America,  vol.  1,  pp.  125-133. 


128 


GLACIERS   OF   NORTH   AMERICA. 


+- 


Along  the  Yukon,  from  its  mouth  to  near  its  source,  one  may  fre- 
quently see  strata  of  clear  ice,  or  more  frequently  of  black,  dirt-'AiaincA 
ice  and  frozen  gravel  several  feet  thick,  in  the  freshly  cut  l/df)ks  <A  th 
stream.  In  general,  throughout  the  low-lying  portions  of  central  AVdHiut 
subsoil  ice  exists  at  a  depth  of  but  a  few  inches  beneath  the  ioyesirfA/z-rfd 
surface.  The  maximum  thickness  of  this  permanently  frozen  layer  ig  jv/ 
known,  but  in  a  few  instances  of  which  I  have  authentic  intormati<»ii,  M 
has  been  penetrated  to  a  depth  of  25  feet  without  reaching  the  bottofti. 

Explorations  conducted  by  Lieut.  J.  C  Cantwell,^  of  the  C  H. 
Revenue  Marine  service,  along  the  Kowak  river,  which  flows  itt*/) 
Kotzebue  sound,  about  260  miles  north  of  the  mouth  of  the  Yukon,  and 
just  within  the  Arctic  circle,  have  shown  that  a  layer  of  subsoil  ice  from 
100  to  200  feet  thick  has  there  been  cut  into  by  the  streams  so  as  to 
leave  steep  bluffs  of  solid  ice  along  their  borders.  The  ice  covers  the 
land  like  a  stratum  of  rock,  and  has  been  dissected  by  stream  erosion  in 
much  the  same  manner  that  river  channels  are  corraded  in  other  regions. 
Above  he  ice  there  is  a  thin  covering  of  rich  black  soil  supporting  a 
growth  of  mosses,  grasses,  and  trees.  Instructive  illustrations  of  the  Kowak 
river  flowing  between  precipitous,  caflon-like  walls  of  ice  are  presented  in 
the  report  just  referred  to. 

One  of  the  most  striking  exposures  of  subsoil  ice  in  Alaska,  and  one  that 
has  been  described  by  many  travelers,  exists  on  the  shore  of  Eschscholtz 
bay  at  the  head  of  Kotzebue  sound.  The  ice  there  forms  a  bold  bluff. 
and  has  been  estimated  to  be  from  150  to  300  feet  thick.  It  is  covered 
with  rich  humus,  on  Avhich  grasses  grow  luxuriantly.  In  this  instance,  as 
in  several  other  similar  examples  that  are  known,  the  ice  contains  the 
bones  of  the  mammoth  and  other  large  animals  that  are  now  extinct. 
The  soil  which  accumulates  as  the  ice  melts,  owing  to  the  concentration 
at  the  surface  of  the  impurities  it  contains,  has  a  strong  odor  of  decayiniT 
animal  matter.  We  are  thus  assured  that  the  subsoil  ice,  in  certain 
instances,  and  probably  over  extensive  areas,  was  formed  at  a  time  so 
remote  that  the  animals  then  inhabiting  the  country  in  great  numbers 
have  sine'*  become  exLlnct. 

The  ice  in  the  banks  of  the  lower  Yukon,  and  in  the  vicinity  of 
Kot'-ebue  sound,  is  a  part  of  a  vast  slieet  of  frozen  subsoil  that  underlies 
large  portions  of  the  low,  marshy  vegion  fringing  the  shores  of  BeriiiLj 

^  'A  Narrative  Accou;it  of  the  Exploration  ot  the  Kowak  River,  Alaska,"  in  Report  "f 
the  Cruise  of  the  Revenue  Marine  Steamer  Cawnn,  hi  the  Arctic  Ore  >  -"  ■  -^ar  18S  j, 
by  Capt  M.  A.  Healy,  Ireasury  Department,  Wa&hhigton.  D.C,  i'.*"" 


..Ltt^>lV^ 


GLAOIEKS   OF   ALASKA. 


129 


4«A  and  the  Arctic  ocean.  This  tundra,  as  it  is  termed,  covers  many 
ffj/msands  of  square  miles.  It  is  bright  with  mosses  and  a  profusion  of 
low,  flowering  plants  during  the  short  Arctic  summer,  but  beneath  its 
iiixuriant  carpet  of  verdure  the  ground  is  always  frozen. 

Still  juore  extensive  tundras  cover  the  low  lands  forming  the  Arctic 
^40^4^  *>i  Asia,  and  have  there  been  penetrated  to  a  depth  of  nearly  400 
(^M  Wl^mut  reaching  the  bottom  of  the  subsoil  ice.  It  is  in  this  deposit 
tl*»t  tlie  complete  carcasses  of  the  mammoth  and  of  the  woolly  rhinoceros 
re  found  from  time  to  time.  The  fossil  ivory  gathered  along  the  banks 
of  the  rivers  in  this  4rctic  region  is  said  to  be  even  more  important  as  an 
article  of  commerce  than  the  elephant  tusks  obtained  in  the  jungles  of 
Africa. 

It  is  not  probable  that  all  of  the  subsoil  ice  of  northern  regions  has 
])een  formed  in  one  way.  Along  the  flood  plains  and  on  the  deltas  of 
rivers  where  layers  of  clear  ice  are  interbedded  with  sheets  of  frozen 
gravel  and  vegetable  matter,  as  is  frequently  the  case,  it  seems  evident 
that  the  growth  of  the  deposit  is  due,  in  some  instances,  to  the  flooding 
of  previously  frozen  layers,  and  the  freezing  and  subsequent  burial  of  the 
sediment  thus  added  to  their  surfaces.  When  spring  freshets  spread  out 
sheets  of  debris  over  the  flood  plain  of  a  river,  as  frequently  happens  when 
streams  in  high  latitudes  flow  northward,  the  previously  frozen  soil  and 
the  ice  of  ponds  and  swamps  may  be  buried  and  indefinitely  preserved. 
During  the  succeeding  winter  the  surface  layer  thus  added  would  itself 
become  frozen,  and  perhaps  in  its  turn  become  buried  beneath  later 
deposits  of  the  same  character  at  intervals  of  one  or  more  years. 

On  the  tundras  the  luxuriant  growth  of  vegetation  that  start'^  into  life 
as  soon  as  the  winter's  snow  has  disappeared,  and  grows  rapidly  during 
the  long,  hot  summer  days,  dies  below  and  partially  decays,  but  becomes 
frozen  and  has  its  complete  destruction  arrested,  while  the  dense  mat  of 
roots  and  stems  above  continues  to  thrive.  In  this  way  an  accumulation  of 
partially  decayed  vegetable  matter  is  formed,  which  increases  in  thickness 
from  year  to  year  by  additions  to  its  surface.  The  process  is  similar  to 
that  by  which  peat  bogs  are  formed  in  temperate  latitudes,  except  that 
the  partially  decomposed  vegetation  becomes  solidly  frozen.  It  is  in 
reality  an  example  of  cold  storage  on  a  grand  scale.  This  slow  accumu- 
lation in  northern  regions  of  vegetable  matter,  together  with  the  bones 
and  even  complete  carcasses  of  animals,  is  truly  a  Avonderful  process. 
Under  existing  climatic  conditions  there  does  not  seem  to  be  any  limit 
to  the  depth  such  deposits  may  ;\ttair..     The  amount  of  carbonaceous 


IP'PliHHSii,"- 


m^ 

■  ^ 

^^n  '1 

[I 


i 


130 


GLACIERS   OF    NOUTH   AMERICA. 


material  already  accumulated  in  the  tundras  of  America  and  Asia  must 
ecjual  that  of  the  most  expensive  coal  field  known.  i  view  of  these 
facts  it  does  not  seem  an  unreasonable  suggestion  thai  '>me  coal  seams 
might  have  originated  from  the  vegetable  matter  accumulated  in  ancient 
tundras. 

There  is  still  another  process  by  which  frozen  subsoil  may  be  formed 
in  higli  latitudes :  this  is,  the  effects  of  the  cold  duiing  the  long  winters 
are  not  counteracted  by  the  heat  during  the  short  summers.  Under  the 
conditions  now  prevailing  in  northern  Alaska,  where  the  mean  annual  tem- 
perature is  below  32°  Fahrenheit,  the  frozen  layer  tends  to  increase  in  thick- 
ness from  year  to  year  just  as  the  depth  of  frozen  soil  in  more  temperate 
latitudes  may  increase  from  month  to  month  during  the  winter  season. 
During  the  sliort  northern  summers,  especially  where  the  gro\ind  is  moss- 
covered,  melting  only  extends  a  few  inches  below  the  surface. 

Computations  made  by  Prof.  R.  S.  Woodward  ^  have  shown  that  the 
freezing  of  even  the  deepest  ice  stratum  yet  discovered  in  Ai'ctic  regions 
might  have  resulted  in  the  course  of  a  few  thousand  years  from  a  mean 
amrual  temperature  no  lower  than  that  prevailing  in  northern  Alaska  at 
the  present  time. 

The  subsoil  ice  described  above  lacki^  most  of  the  characteristics  of 
glaciers  aaad  should  not  he  included  among  them.  It  is  so  closely  analo- 
gous, however,  to  the  condition  reached  by  continental  and  i>iedmont 
glaciers  when  they  iwecome  stagimiit  and  are  wasting  away,  that  the  mode 
of  its  formation  i-eiris  to  be  understood  in  order  that  the  two  may  not  be 
confounded-  The  liniiitic  conditi'v  .s  admitting  of  the  accumulation  of 
subsoil  ^  simiar.  uud  probaLly  identical,  to  those   which    initiate 

glacial  p'u it  MCT.  Im  times  immediately  ]ireceding  the  formation  of  conti- 
nental <]^u.'iers,  it  ie  p«i<«ible  that  subsoil  ice  like  ♦^hat  of  the  tundras  may 
be  formed  over  extensive  regions  before  they  become  covered  by  a  flowing 
ice  sheet.  In  soeli  an  instance  the  frozen  subsoil  might  become  a  part  of  a 
continental  giaeier  when  covered  by  the  advancing  ice.  During  the 
amelioration  of  climate  following  an  ice  invasion,  the  tundra  phase  might 
again  return,  so  that  a  glacial  p<n"iod  would  l)e  lx«th  preceded  and  followed 
by  a  time  when  the  mean  annual  temperature  would  tavor  the  existence 
of  deeply  frozen  subsoil,  and,  at  the  same  tmie,  adnut  of  the  grow  th  of 
luxuriant  forests. 

1  Geological  Society  of  America,  Buleti'i   vol.  1,  pp.  131,  132. 


CHAPTER   VII. 


^mm. 


GLACIERS  IN  THE  GREENLAND  REGION. 

Grlnncll  Land. —  Explorations  in  tlie  extreme  northeastern  part  of 
North  America  have  been  carried  on  principally  along  the  navigable  water 
ways.  It  is  only  recently  that  a  knowledge  has  been  gained  of  the  vast 
snow  fields  in  which  the  glaciers  descending  to  the  sea  have  their  origin. 
The  most  instructive  journeys  that  have  been  made  on  the  islands  to  the 
west  of  Baffin's  bay,  Davis  strait,  etc.,  were  by  membei-s  of  the  Lady 
Franklin  Bay  expedition  in  1882.  Gen.  A.  W.  (Jreely,  in  his  admiral)le 
account  of  "  Three  Yeai-s  of  Arctic  Service,"  describes  the  United  States 
mountains  in  the  northern  part  of  Grinnell  land,  as  being  buried  beneath 
neve  snow,  and  apparently  presenting  much  the  >.ime  appear.) nee  as  the 
desolate  region  to  the  north  of  Moiuit  St.  Elias,  described  in  the  preceding 
chapter. 

The  largest  ice  stream  draining  the  snow  lields  rif  (h-innell  land  yet 
discovered,  known  as  the  Henrietta  Nesmith  glacier,  floww  south  and 
terminates  near  Lake  Hazen.  The  most  striking  feature  of  tins  great 
glacier,  and  one  that  seems  to  l)e  characteristic  of  many  rrf  the  ice  streams 
of  the  far  north,  is  the  extremely  i)r»*ipitous  sloi)e  in  which  it  terminates. 
As  shown  in  an  illustration  pid)lishefl  by  General  Greely.  its  exteemity  i» 
a  nearly  vertical  wall  of  ice,  perliaps  150  or  200  feet  high.  Tlie  main 
glacier  is  formed  by  the  union  of  five  ia<lependent  streams,  whicii  pour 
doAvn  from  an  extensive  ice  cap  to  th«-  north  of  the  Garfield  range  and 
south  of  the  United  States  mountains.  A  tributary  from  tin-  "  '  -ins 
the  main  glacier  about  four  miles  above  its  terminus,  and  ;t  ^<-<.  ymu  and 
third  tributary  comes  in  from  the  northeast  about  seven  am^  ten  miles, 
respectively,  inland.  The  main  glacier  is  separated  from  the  lowest  tribu- 
tary by  a  roundeH  mountain  s])ur,  which  from  the  statif)n  occupied  hj 
the  explorer  cut  off  the  view  in  that  direction.  In  all  other  (juaitei's, 
liowever,  the  view  was   unobstructed,  and    embraced   aboet   18  degrees 

of  aZimUthr— i- _„-_--,-_-.. -,.;.-,„i.-..-,.., „:._^^^-„ , ,_.;^_._-,--:,,,_i>.,_;-^-^:„. 

The  description*)  and  sketches  published  by  Greely  seem  to  show  that 
the  United  States  mountains  are  covered  with  a  general  neve  field  through 
which  the  higher  peaks  project,  and  that  large  glaciiers,  resembling  most 


T 


132 


GLACIERS   OF    NORTH   AMERICA. 


I 


nearly  those  of  the  ai|)ine  type,  descend  from  the  snow-covered  uplands 
in  various  directions.  The  ice  streams  flowing  southward  are  the  l)est 
known,  although  hut  hastily  examined,  as  explorations  have  heen  carried 
nearest  to  the  mountains  in  that  direction. 

Reports  hy  Lieut.  J.  li.  Lockwood  and  Serg.  D.  L.  Brainard  ^  of 
explorations  across  Griimell  land  from  Archer  fiord  on  the  east  to  Greely 
fiord  on  the  west,  show  that  the  land  hoth  to  the  north  and  south  of  thti 
route  followed  is  heavily  covered  with  snow  fields  and  glaciere.  The 
region  to  the  south,  especially,  is  mounttiinous,  and  the  higher  peaks  and 
domes  alone  reveal  their  forms  ahove  the  all-pervading  snow  fields.  From 
this  elevated  neve  a  vast  glacier  or  series  of  more  or  less  confluent 
glaciers,  named  "Mer  de  Glace  Agassiz,"  flows  northward,  and,  hreakiiij.^ 
into  individual  ice  streams,  send  out  branches,  some  of  which  become  tide- 
water glaciers  on  reaching  Greely  fiord.  The  most  remarkable  feature  of 
the  glaciers  seen  by  Lockwood  and  Brainard,  as  in  the  case  of  the  Henri- 
etta Nesmith  glacier,  is  the  precipitous  manner  in  which  the  ice  ends. 
The  glaciers  seem  to  terminate  on  the  land  as  abruptly  as  do  tide-water 
glaciers  in  more  southern  latitudes  on  entering  the  sea.  The  long  line 
of  ice  cliffs  marking  the  northern  margin  of  Mer  de  Glace  Agassiz  is 
termed  the  "Chinese  Wall"  in  the  report  referred  to,  and,  as  shown  in 
sketches,  when  seen  from  the  north  present  the  appearance  of  a  vast  wall 
of  ice  trending  across  the  country  in  a  general  east  and  west  direction, 
and  forming  an  escarpment  apparently  two  or  three  hundred  feet  higli. 
Kising  beyond  this  wAi  of  ice,  and  seen  over  its  crest,  are  the  snow 
fields  and  bald,  snow-covered  mountains  where  the  great  glacier  has 
its  source. 

From  what  is  known  of  Grinnell  land  it  appears  that  the  glaciers 
covering  its  more  elevated  portions  are  of  the  alpine  tyj;»e,  but  differ  from 
the  glaciers  in  the  mountainous  portions  of  more  southern  lands  for  the 
reason  that  their  gathering  grounds  are  comparatively  low,  and  also 
because  the  snowfall  is  light  and  melting  greatly  retarded.  The  result  is 
that  glaciei-s  of  great  size  are  formed  in  regions  but  little  elevated  above 
the  sea,  and  that,  from  some  combination  of  conditions  not  yet  fully 
explained,  they  end  abruptly  in  precipitous  escarpments.^ 


'  Tn  ""Tieport  of  the  Proceedings  of  the  U.  S.  Expedition  to  Lady  Franklin  Bay,"  by 
A.  W.  Greely,  Washington,  1888,  vol.  1,  pp.  274-206. 

'•*  Since  this  book  was  written,  Prof.  T.  C.  Chamberlin  has  made  a  study  of  some  of  the 
glaciers  of  Greenland,  and  has  suggested  that  the  low  angle  of  incidence  of  the  sun's  rays  in 
the  far  north  may  explain  the  peculiar  manner  in  which  the  glaciers  there  terminate. 


GLACIERS    IN    THE   GKEENLAND   llEOlON. 


133 


The  general  climatic  and  topographic  conditions  characterizing  Grin- 
iiell  land  seem  to  extend  southward  and  cnd)race  neighlK)ring  land  areas, 
i)ut  explorers  have  yet  to  discover  the  limits  of  the  glaciei^s  in  that  region, 
and  to  make  more  critical  studies  of  the  entire  glacial  system  of  the  north- 
eastern corner  of  the  continent. 


^np 


Greenland. 

While  the  northern  shore  of  Greenland  remains  unexplored  it  will  he 
impossible  to  determine  the  full  extent  of  the  land  or  of  the  ie3  sheet 
covering  it.  From  the  most  reliable  data  available,  however,  it  is  probable 
that  the  land  is  about  1500  miles  long  from  north  to  south,  and  800  miles 
broad  in  the  widest  portion.  As  estimated  by  Lieut.  II.  E.  Peary,  i  .8 
area  is  apiwoximately  750,000  square  miles,  of  which  fully  000,000  are  ice 
and  snow  covered. 

The  interior  of  Gregnland  is  reported  by  the  few  bold  explorers  who 
have  crossed  it  to  be  completely  buried  beneath  a  featureless  plain  of 
snow.  This  covering  has  reached  such  a  dei)th  in  all  of  the  central  part 
that  not  a  single  mountain  peak  is  known  to  break  the  even  monotony  of 
its  surface.  The  snow  is  highest  and  prcyr>ably  deepest  in  the  central  area, 
and  descends  toward  the  coast,  thus  giving  the  island  a  convex  surface. 
The  general  elevation  of  the  central  portion  is  from  7000  to  8000  feet, 
decreasing  gradually  toward  the  coast,  especially  to  the  east  and  west,  where 
the  glaciers,  protruding  like  great  tongues  of  ice  from  the  central  regi'^>n, 
come  down  to  the  sea.  The  only  mountain  peaks  that  rise  above  the 
surface  of  the  general  covering  of  snow  are  within  from  50  to  75  miles  of 
the  coast.  These  partially  buried  peaks  rise  like  islands  in  the  sea  of 
white.  They  are  known  to  the  inhabitants  of  the  coast  as  nunataks;  a 
convenient  name  that  has  found  a  place  in  geological  literature. 

The  depth  of  the  nearly  universal  covering  of  snow  and  ice  under 
which  Greenland  is  buried  canno-t  Ije  told,  as  it  is  impossible  to  determine 
ihe  topography  of  the  land  beneath.  The  best  esti  nates  that  can  be  made 
place  its  depth  at  several  thousand  feet.  In  the  central  portion,  where 
the  covering  is  apparently  thickest,  its  depth  may  be  fully  equal  to  the 
height  of  the  surface  above  the  sea,  or  about  8000  feet. 

Like  the  n^v^s  of  smaller  glaciers,  the  surface  of  all  the  central  part 
of  the  Greenland  ice  sheet  is  composed  of  light  granular  snow.  This 
greatest  of  all  n^ves  in  the  northern  hemisphere  is  remarkably  uniform  in 
contour  and  unbroken  by  crevjisses  and  unscored  by  water  courses  in  all 


134 


GLACIERS   OF   NOIITII    AMERICA. 


of  itH  central  area.  The  ice  formed  Injueath  the  ii^'ve  in  the  interior  flows 
outward  iii  all  directions  through  the  ])asse.s  in  the  mountains  in  independ- 
ent ice  streams,  many  of  which  reath  the  ocean  and  form  the  largest  tide- 
water glaciers  known,  with  the  exception  of  those  in  Antarctic  regions. 
One  of  the  grandest  of  these  tongues  of  ice  is  the  Humboldt  glacier,  whidi 
flows  westward  ami  discjiarges  into  Kane  basin  in  about  latitude  7U°  8U'. 
The  extremity  of  this  glacier,  exi)lorcd  and  named  by  Dr.  Kane,  forms  a 
wall  of  ice  that  is  reported  to  be  40  miles  long  and  from  'J"0  to  800  feet 
high  above  the  sea.  The  veritable  mountains  of  ice  thatbnnik  away  from 
tlie  partially  submerged  face  are  of  astonishing  dimensions,  and  in  many 
instances  find  their  way  southward  through  BalVm's  bay  to  the  banks  of 
Newfoundland,  and  endanger  the  safety  of  trans-Atlantic  steamers. 

At  many  localitikjs  about  the  Ijorders  of  Greenland,  the  rough,  broken 
extremities  of  glaciei-s  similar  to  Humboldt  glacier  are  known  to  enter  the 
sea.  The  adjacent  waters  are  crowded  with  bergs  shed  off  by  these  tide- 
water glaciers,  and  also  with  floe  ice  originating  from  the  freezing  of  sea 
water.  In  numerous  instances  the  tide-water  glaciers  end  at  the  heads  of 
deep  fiords,  as  in  tiie  case  of  many  Alaskan  glaciei-s.  Again,  the  ice 
terminates  on  land  and  presents  steep,  broken  surfaces,  that  are  so  deei)ly 
gashed  and  so  shattered  into  pinnacles  and  spires  that  it  is  imi)ossible  to 
cross  them.  When  tlie  topography  of  the  high  lands  bordi'ring  the  coast 
is  not  favorable  to  the  formation  of  tongue-like  glaciers  in  deep  valleys, 
the  ice  from  the  great  interioi  reservoir  presses  outwaid  and  terminates 
in  blue  cliffs  high  up  on  rocky  slopes,  but  melts  before  descending  to  the 
sea.  The  rocks  now  bordering  the  glaciers,  and  in  part  confining  them, 
are  in  many  localities  rounded,  smoothed,  and  striated,  showijig  that  in 
former  times  the  ice  inundations  were  much  more  extensive  than  at 
present,  and  reached  the  sea  on  every  hand.  In  other  localities,  as 
recently  determined  by  Chamberlin,  the  land  near  the  west  coast  has 
never  been  ice-covered.  A  small  driftless  area  on  the  shove  of  Ingerfield 
gulf  is  one  of  the  most  interesting  discoveries  made  in  Greenland  in  recent 
years,  and  shows  th.at  the  previously  entertained  idea  that  during  former 
periods  of  maximum  glaciation  the  land  was  entirely  ice-covered  is 
incorrect.  -"' 

The  information  now  in  hand  concerning  the  Greenland  ice  sheet  is 
the  result  of  combined  observations  of  many  explorers.  Space  will  not 
admit  of  an  historical  review  of  the  slow  progress  that  has  been  made  in 
gathering  information  of  scientific  value  in  the  far  north,  but  the  student 
who  desires  to  follow  up  the  subject  will  find  the  necessary  references  in 


OLACIEUS    IN    THE   OKEENLAND   REGION. 


185 


the  summaries  of  the  j,'eoh)p[iejil  results  of  northern  exphuation  iiulieated 
in  the  f'>] lowing  footnote.^ 

The  rough  ice  met  with  on  the  borders  of  Greenland  has  been 
deseril)ed  by  many  writei-s.  >(Miih  of  al)out  latitude  70°  it  presents  the 
(  haraeteristies  of  the  lower  extremities  of  alpine  glacici-s  in  less  remote 
regions.  In  the  northern  part  of  the  continent,  however,  it  ends  in 
exceptionally  ]ireci])itous  :  'opes.  T'le  tongue  (»f  ice  reaching  seaward 
between  bold  U[)lands  on  the  west  coast  near  Disco  island,  in  latitude  (11)° 
^}0',  is  a  characteristic  examj)le  of  what  may  be  seen  at  many  other  local- 
ities on  the  M'ild  (ireenland  coast.  This  protrusion  of  the  island  ice  is 
described  by  Lieutenant  Penry  as  follows  : 

"  Wherever  the  ice  projects  down  a  valley  in  a  long  tonguf  or  stream, 
the  edges  contract  and  shrink  away  from  the  warmer  ro<ks  on  each  side 
having  a  deep  cailon  between,  usually  occupieil  by  a  glacial  stream.  .  .  . 
Higher  up,  along  the  unbroken  portion  of  the  dam  [i.e.  enclosing  moun- 
tains], where  the  rocks  have  a  southern  ex})osure  or  rise  mucli  above  the 
ice,  there  is  apt  to  be  a  deep  cailon  between  the  ice  and  the  rocks ;  the 
ice  face,  sometimes  CO  feet  high,  puic,  pale  green,  and  flinty.'-^  In  another 
place  the  ice  face  may  be  so  striated  and  discoloied  as  to  be  a  pi.cise 
<'()unterpart  of  the  rock  opposite,  looking  as  if  torn  from  it  by  some  con- 
vulsion. The  bottom  of  the  cailon  is  almost  invariably  occupied  by 
water.  .  .  .  Still  farther  up,  at  the  very  crest  of  the  dam,  the  ice  lies 
iimoothly  against  the  rocks. 

"As  to  the  features  of  the  interior  beyond  the  coastlim;,  the  surface 
of  the  '  ice  blink '  near  the  margin  is  a  succession  of  rounded  hummocks, 
steepest  and  highest  on  their  landward  sides,  which  are  sometimes  pre- 
cipitous. Farther  in  these  hummocks  merge  into  long,  flat  swells,  which 
in  tuin  decrease  in  height  toward  the  interior,  until  at  last  a  flat,  gently 
rising  plain  is  reached,  which  doubtless  becomes  ultimately  level." 

The  great  Humboldt  glacier,  alieady  I'eferred  to,  j)resents  another 
example  of  the  characteristic  scenery  of  the  Greenland  coast,  as  is  shown 
by  th.i  following  graphic  description  by  Dr.  Kane  : 

1  Dr.  II.  Rink,  "  Results  of  the  Recent  Danish  Explorations  in  Greenland  with  Recjard 
to  the  Inland  Ice  (1878-18d9),"  in  Edinburg  G.jol.  Soc.  Trans., vol.  5,  1888,  pp.  ii80-20;i. 
Dr.  F.  Nansen,  "  Firet  Crossing  of  Creenland,"  vol.  1,  pp.  450-610. 
n.  Frederick  Wright,  'Ice  Age  in  No"th  America,"  pp.  07-01. 

Warren  Upham,  "The  Ice  Sheet  of  Greenland,"  in  American  Geologist,  vol.  8,  1804, 
pp.  14     152. 
__^  Jumes  Geikie,  "The  Great  Ice  Age,"  3d  ed.,  1894,  pp.  42-61. 

T.  C.  Chamberlin,  in  the  Geological  .louriial  (Chicago)  for  1804-1896. 
^  American  Geographical  Society,  Bullet  i  i,  vol.  19,  1887,  p.  286. 


Lfl 


'^ 


^, 


IMAGE  EVALUATION 
TEST  TARGET  (MT-S) 


^'C? 


^   A 


^^^  «:•. 


.'!'/ 


« 


/. 


f/i 


(/. 


t 


1.0 


11.25 


|45 


***     836       « 


125 
2.2 


I.I     !,■*  lis 

U    11.6 


V 


v>    -*>. 


^  :> 


V 


Sdences 
Corporation 


23  WSST  MAIN  STREET 

WEBSVER.N.Y.  14C;80 

(716)  872-4503 


^ 


[v 


:17 


<> 


6^ 


t 


V 


'<^ 


''b 


vV 


136 


GLACIEKS   OF   NOllTli    AMEltlCA. 


"  The  trend  of  this  glacier  is  n,  few  degrees  to  the  west  of  north.  We 
followed  its  tace  eastward,  edging  in  for  the  Greenland  coast,  about  tin; 
ro^ky  archipelago  which  I  have  named  after  the  Advance.  From  one  of 
these  rugged  islets,  the  nearest  to  the  glacier  which  could  be  approached 
with  anything  like  safety,  I  could  see  another  island  larger  and  closer  in 
shore,  already  half  covered  by  the  encroaching  face  of  the  glacier,  and 
great  masses  of  ice  still  detaching  themselves  and  splintering  as  they  fell 
upon  the  poitions  which  protruded.  Repose  was  not  the  characteristic  of 
this  seemingly  solid  mass ;  every  feature  indicated  activity,  eneig\ , 
movement. 

"  The  surface  seemed  to  follow  that  of  the  adjacent  country  over  which 
it  flowed.  It  was  undulating  about  the  horizon,  but  as  it  descendeil 
toward  the  sea  it  represented  a  broken  plain  with  a  general  inclination  of 
some  nine  degrees,  still  diminishing  toward  the  foreground.  Crevtisses, 
in  the  distance  mere  wrinkles,  expanded  as  they  came  nearer,  and  were 
crossed  almost  at  right  angles  by  long  continuous  lines  of  fracture  parallel 
with  the  face  of  the  glacier. 

"  These  lin^s,  too,  scarcely  traceable  in  the  far  distance,  widened  as 
they  approached  the  sea,  until  they  foimed  a  gigantic  stairway.  It  seemed 
as  though  the  ice  had  lost  its  support  belov  und  that  the  mass  was  let 
down  from  above  in  a  series  of  steps.  Such  an  action,  owing  to  the  heat 
derived  from  the  soil,  the  excess  of  surface-drainage,  and  the  constant 
abrasion  of  the  sea,  must  in  reality  take  place.  The  indications  of  a  great 
propelling  agenc}'  seamed  to  bo  just  commencing  at  the  time  I  was  observ- 
ing it-  These  split-off  lines  of  ice  were  evidently  in  motion,  pressed  on 
by  those  behind,  but  still  widening  their  fissures,  as  if  he  impelling^ 
action  was  more  energetic  near  the  water,  till  at  last  they  floated  away  in 
tlie  form  of  icebergs.  Long  files  of  these  detached  masses  could  be  traced 
slowly  sailing  off  into  the  distance,  their  separation  marked  by  dark 
parallel  shadows  —  broad  and  spacious  avenues  near  the  eye,  but  narrowed 
in  the  perspective  to  mere  lines.  A  more  impressive  illustration  of  the 
forces  of  nature  can  hardly  be  conceived.  ,  .  . 

"  The  frozen  mass  before  me  was  similar  in  structure  to  the  Alpine  and 
Norwegian  ice  growths.  It  would  be  foreign  to  the  character  of  this  book 
to  enter  into  the  discussion  which  the  remark  suggests  ;  but  it  will  be 
seen  by  the  sketch,  imperfect  as  it  is,  that  their  face  presented  nearly  all 
the  chamcteristic  features  of  the  Swiss  Alps.  The  'overflow,'  as  I  ha\t' 
called  the  viscous  overlapping  of  the  surface,  was  more  clearly  marked 
than  upon  any  Alpine  glacier  with  which  I  am  acquainted.     When  close 


GL4CIE11S   IN  THE   GREENLAND   REGION. 


187 


i 


to  the  island  rocks  and  looking  out  upon  the  upper  table  of  the  glacier,  I 
was  struck  with  the  timely  analogy  of  the  batter-cake  spreading  itself 
under  the  ladle  of  the  housewife,  the  upper  surface  less  affected  by 
friction,  and  rolling  forward  in  consequence. 

•  ''  The  crevasses  bore  the  mark  of  direct  fracture  and  the  more  gradual 
action  01  surface  drainage.  The  extensive  watershed  between  their  con- 
verging planes  gave  to  the  icy  surface  most  of  the  hydrographic  features 
of  a  river  system.  The  ice-born  rivei-s  which  divided  them  were  margined 
occasionally  with  spires  of  discolored  ice  and  generally  lost  themselvef?  in 
the  central  area  of  the  glacier  before  reaching  its  foreground.  Occasion- 
ally, too,  the  face  of  the  glacier  was  cut  by  vertical  lines,  which,  as  in  the 
Alpine  growths,  were  evidently  outlets  for  the  surface  drainage.  Every- 
thing was,  of  coui-se,  bound  by  solid  ice  when  I  looked  at  it ;  but  the 
evidence  of  torrentr-action  was  unequivocal,  and  Mr.  Bonsall  and  Mr. 
Morton,  at  their  visit  of  the  preceding  year,  found  both  cascades  and 
water  tunnels  in  abundance. 

"  The  height  of  this  ice  wall  at  the  nearest  point  was  about  300  feet, 
measured  from  the  water's  edge  ;  and  the  unbroken  right  line  of  its 
diminishing  perspective  showed  that  this  might  be  regarded  as  its  con- 
stant measurement.  It  seemed,  in  fact,  a  great  icy  table-land  abutting 
with  a  clean  precipice  against  the  sea.  This  is,  indeed,  characteristic  of 
all  those  Arctic  glaciers  which  issue  from  central  reserviors,  or  .ners  de 
glace,  upon  the  fiords  or  bays,  and  is  strikingly  in  contrast  with  the  de- 
pendent or  hanging  glaciers  of  the  ravines,  whose  every  line  and  furrow 
and  chasm  seems  to  indicate  the  movement  of  descent  and  the  mechanical 
disturbances  which  have  retarded  it.  .  .  . 

"  As  the  surface  of  the  glacier  receded  to  the  south,  its  face  seemed 
broken  with  piles  of  earth  and  rock-stained  rubbish,  till  far  back  in  the 
interior  it  was  hidden  from  me  by  the  slope  of  a  hill.  Still  beyond  this, 
however,  the  white  blink  or  glare  of  the  sky  above  showed  its  continued 
extension. 

"  It  was  more  difficult  to  trace  this  outline  to  the  northward  on  account 
of  the  immense  discharges  at  its  base.  The  talus  of  its  descent  from  the 
interior,  looking  far  off  to  the  east,  rangec'  from  seven  to  fifteen  degrees, 
so  broken  by  the  crevasses,  I-owever,  as  to  g'-.e  the  PlTect  of  an  inclined 
plane  only  in  the  distance.  A  few  black  knobs  rose  from  the  white  snow 
like  islands  from  the  sea.  The  general  configuration  of  its  surface  showed 
how  it  adapted  itself  to  the  inequalities  of  the  basin-country  beneath. 
There  was  every  modification  of  hill  and  valle}',  just  as  upon  land." 


* 

'■:r 
I 

i 


I 


138 


GLACIERS   OF   NOKTH   AMEUICA. 


III" 


'  The  margin  of  the  inland  ice  on  the  east  side  of  Greenland  has  been 
explored,  especially  by  Nansen,  and  found  to  have  the  same  general  char- 
acteristics as  on  the  tvest  coast,  excepting  that  the  strip  of  mountainous 
country  intervening  between  the  sea  of  ice  in  the  interior  and  the  ben  of 
water  to  the  east  is  nariov/er,  and  the  ascent  steeper.  Several  large  glaciers . 
are  known  on  the  east  ccas^  similar  in  character  to  the  Humboldt  glacier, 
and  the  adjacent  watera  are  crowded  with  icebergs  and  with  floe  ice. 

The  northern  coast  of  Greenland,  at  least  as  far  as  Cape  Washington, 
the  present  limit  of  exploration,  was  found  by  Lockwood  and  Brainard  to 
be  formed  by  bold  rock  headlandd  separated  by  deep  valleys  and  wild, 
desolate  fiords.  The  mountains  are  snow-covered,  but  glaciei"s  are  not  a 
conspicuous  feature  of  the  stern  landscape,  and,  so  far  as  known,  none  of 
them  reach  the  sea.  I'he  character  of  the  coast  as  seen  from  Cape 
liiitannia,  lat.  82°  45',  is  indicated  in  the  following  description  bj  Liea- 
tenant  Lockwood :  ^ 

"  Owing  to  the  continued  bad  weather  my  view  of  the  interior  was 
mainlj^  confined  to  what  I  saw  from  the  two  elevations  recorded  ;  and 
owing  to  their  comparative  lowness,  the  range  of  mountain  peaks,  with 
their  universal  covering  of  snow,  merging  and  overlapping  one  another, 
made  it  very  difficult  to  distinguish  the  topography  at  all.  The  interior 
land  seemed  very  high  and  on  this  account  the  farthest  that  I  could  see 
could  not  have  been  very  many  miles  removed.  I  could  see  (from 
Britannia  and  Lockwood  islands)  no  glaciers  that  I  could  recognize  as  such, 
though  from  the  floe,  while  traveling,  I  saw  a  very  large  one  and  one  or 
two  quite  small.  From  my  farthest  I  saw  mountains  to  the  east,  perhaps 
twenty  or  thirty  miles  distant,  and  a  high  mountainous  country  doubtless 
exists  along  this  coast  for  some  distance  to  the  south;  the  ^hore  line  of  the 
fiords  invariably  begin  at  the  base  of  steep  cliiBfs  and  mountains.  No  land 
was  seen  to  the  north.  There  was  a  very  noticeable  abundance  of  snow 
everywhere." 

The  above  observations  on  the  snowy  covering  of  the  north  coast  of 
Greenland  were  made  in  May.  Judging  from  the  reports  of  Lieutenant 
Peary,  who  found  an  abundance  of  flowers  at  the  farti.est  point  reached 
during  his  overland  journey,  much  of  the  land  seen  by  Lockwood  must  be 
bare  of  snow  in  late  summer. 

Far  to  the  north,  as  discovered  by  Lieutenant  Peary  during  his  fii-st 
famous  journey  over  the  inland  ice,  the  fringe  of  mountains  bordering  the 

1  "Report  of  the  Proceedings  of  the  U.  S.  Expedition  to  Lady  Franklin  Bay,"  vol.  1, 
p.  188. 


mi 


GLACIERS    IN    THE   GltEENLAND    REGION. 


139 


coast  of  Greenland  and  intervening  between  the  vast  snow  plateau  of  the 
Ulterior  and  the  shore  line,becomes  broader,  and  the  inland  ice  is  limited 
in  that  direction  in  about  the  same  manner  as  on  the  better-known  ^/^r- 
tions  of  the  coast  to  the  southward.  The  termination  of  the  inland  ice 
before  reaching  the  northern  border  of  the  land  is  a  signiticant  fact,  which, 
taken  in  connection  with  the  unglaciated  condition  of  northern  Alaska, 
suggests  that  possibly  the  north  end  of  Greenland  was  free  of  ice  even 
during  the  glacial  period. 

The  combined  observations  of  many  explorere  show  that  the  great 
reservoir  of  snow  and  ice  covering  central  Greeidand,  ond  supplied  solely 
from  the  atmosphere,  overflows  in  all  directions  through  passes  in  the 
bordering  mountains  so  as  to  form  separate  ice  tongues,  but  does  not  enter 
the  sea  bodily,  as  one  might  say,  on  any  considerable  portion  of  its 
boundary.  In  this  respect  the  continental  glacier  of  the  northern  hemi- 
sphere differs  from  the  similar  ice  body  in  Antarctic  regions,  which  for  a 
large  part  of  its  periphery  extends  out  into  the  sea,  and  forms  continuous 
ice  cliffs  several  hundred  miles  long.  Two  phases  in  the  existence  of  con- 
tinental glaciers  are  thus  illustrated.  The  one  at  the  north  is  a})parently 
receding  and  contracting  its  boundaries,  while  the  one  at  the  south  is  yet 
in  its  full  vigor,  and  is  possibly  still  increasing. 

Thanks  to  the  daring  and  zeal  of  a  few  explorers  who  have  traversed 
the  interior  of  Greenland,  we  know  what  the  surface  of  a  continental 
glacier  is  like,  and  are  enabled  to  picture  with  considerable  confidence  the 
character  of  large  portions  of  North  America,  now  thickly  peopled,  as  it 
existed  during  the  height  of  the  glacial  period. 

The  first  successful  attempt  to  pass  beyond  the  rugged  borders  of 
Greenland  and  travel  on  the  snow  surface  of  the  interior,  was  made  by  the 
celebrated  Swedish  navigator.  Baron  Nordenskiold,  in  1883.  Leaving  the 
west  coast  a  little  to  the  south  of  Disco  bay,  he  traveled  inland  for 
eighteen  days  over  a  continuous  snow-covered  ice  field  v  hich  presented  the 
characteristic  features  of  the  neve  of  Alpine  glaciei-s,  ajid  rose  gradually 
higher  and  higher  the  farther  he  proceeded.  The  region  of  nunataks  was 
[.assed  and  a  bold  advance  made  over  the  clear  unbroken  surface  of  the 
inland  ice  which  stretched  away  to  the  horizon  as  a  boundless  sea  of  un- 
broken snow.  About  the  only  conspicuous  details  of  the  surface  were 
channels  in  which  clear,  swift  streams  coursed  along  between  walls  of  ice. 
These  streams  were  short,  however,  as  they  soon  i)lunged  into  crevasses  or 
moulins  and  disappeared  to  join  the  general  subglacial  drainage.  The 
murmur  of  waters  far  below  the  surface  told  of  streams  flowing  in  icy 


f 


140 


GLACIEKS    OF    NORTH    AMEUICA. 


ii 


caverns  beneath  We  now  know  that  these  features  pertain  to  the  outti 
border  of  the  ice  sheet,  extending,  it  is  true,  some  distance  iidand  beyond 
the  fringe  of  nunataks,  but  are  wanting  over  the  greater  part  of  the 
central  region. 

At  tlie  end  of  his  inland  journey  Nordenskiold  reached  a  locality 
about  73  miles  from  the  coast  and  an  elevation  of  5000  feet.  He  then 
sent  his  two  Lap  companions  forward  on  nki^  or  Norwegian  snow-shoes, 
for  a  distance,  it  is  estimated,  of  approximately  65  miles,  or  138  miles  from 
the  starting  point  on  the  coast.  The  elevation  at  the  farthest  poiiu 
reached  is  reported  as  being  5850  feet  above  the  sea.  To  the  eastward 
the  surface  still  continued  to  rise,  showing  that  the  summit  of  the  ice  sheet 
was  not  gained.  Nansen^  has  given  reasons  for  concluding  that  the  dis- 
tance traversed  by  the  Lapps  after  leaving  the  main  party  was  over- 
estimated, and  that  in  reality  the  farthest  point  reached  was  but  118  miles 
inland. 

The  explorations  on  the  inland  ice  made  by  Nordenskiold  decided  once 
for  all  that  thj  previously  entertained  hypothesis  in  reference  to  the 
presence  of  an  area  in  the  interior  of  Greenland  free  from  ice  and  perh.ips 
inhabited  is  untenable. 

In  1888,  Lieut.  R.  E.  Peary,  who  has  since  made  thref.  remarkable 
journeys  on  the  inland  ice  of  northern  Greenland,  made  a  reconnoissance 
in  company  with  Chrit^tian  Maigaara,  a  Danish  officer  in  the  Greenland 
service,  to  the  east  of  Disco  bay,  and  some  75  or  100  miles  north  of  the 
route  followed  by  Nordenskiold.  During  this  reconnoissance  Peary  ad- 
vanced about  100  miles  from  the  coast  and  reached  an  elevation  of  7525 
feet  on  the  unbi'oken  surface  of  the  inland  ice. 

Impo'-tant  as  was  the  first  venture  that  Peary  made  into  the  unex- 
plored interior  of  Greenland,  it  has  been  far  surpassed  both  by  Nansen  and 
by  Peary  himself  in  subsequent  years 

Dr.  Fridtjof  Nansen,  the  most  intrepid  of  Arctic  explorers,  with  four 
companions,  crossed  Greenland  from  east  to  west  in  1888,  between  lati- 
tudes 64°  10'  and  64°  15'.  The  width  of  the  ice  was  there  found  to 
be  275  miles.  Where  the  line  of  march  began  the  ice  descended  to  tlu' 
sea  and  formed  a  tide-water  glacier-  but  on  the  west  it  did  not  reach  within 
about  14  miles  of  the  head  of  Ameralik  fiord,  or  70  miles  from  the  outer 
coastline.  The  highest  position  of  the  vast  convex  covering  of  ice  under 
which  the  land  is  buiied  was  8920  feet.  This  elevation  was  reached  at  a 
distance  of  112  miles  from  the  east  coast.  The  gain  in  elevation  for  the 
1  "The  Fii-st  Crossing  of  Greenland "  (Longmans  &  Co.,  London,  1890),  vol.  2,  p.  468. 


GLACIERS    IN   THE   GHEKNLAND    KEGIOxV, 


141 


lirst  15  miles  was  220  feet  per  mile,  and  ihence  to  the  summit  38  feet  per 
mile.  As  tiie  explorers  proeeeded  westward  from  the  summit  the  deseent 
was  still  more  {gentle,  and  for  fully  100  miles  averaged  alxiut  25  feet  per 
mile,  a  slope  which  no  eye  could  distinguish  from  a  perfect  plain.  A 
cross  profile  of  the  inland  ice  was  thus  obtained,  which  shows  a  moderate 
descent  towards  the  oce'.in  on  either  hand,  with  a  broad,  gently  convex  cen- 
tral portion,  and  illustrates  the  form  assumed  by  an  ice  sheet  as  the  result 
of  accumulation  at  the  surface  and  an  outflow  towards  the  margin. 

The  highly  instructive  journeys  made  by  Peary  in  1892,  and  repeated 
in  part  in  1894  and  still  again  in  1895,  northejistward  from  Inglelield  gulf 
on  the  west  coast,  in  about  lat.  77°  30',  confirmed  the  conclusions  reached 
during  the  previous  ex])lorations  referred  to  in  respect  to  the  character  of 
the  Greenland  ice  sheet,  and  seemed  to  define  its  northern  boundary,  at 
least  in  a  general  wav.  In  the  far  north  the  coast  exhibits  the  same 
rugged  character  as  at  the  south.  The  border  of  the  iidand  ice  is  broken 
by  nunataks,  but  the  central  part  forms  a  vast  plain  of  snow  over  whicli 
one  may  travel  with  dog-sleds  and  snow-shoes  for  hundreds  of  miles  in  a 
continuous  line  without  meeting  serious  obstructions.  So  far  as  the  to})Og- 
raphy  is  concerned  it  is  only  near  the  outer  margin,  where  the  ice  flows 
between  rugged  highlands  and  mountains  tops  project  above  its  surface, 
that  serious  difiiculties  to  travel  are  met  with.  The  highest  point 
reached  )n  the  broad,  gently  convex  surface  of  the  ice  at  the  north  was 
about  8000  feet. 

The  principal  lesson  of  geological  interest  learned  from  the  study  of  the 
continental  glaciei-s  covering  Greenland  is  that  such  glaciera  may  originate 
on  land  that  is  not  mountainous  and  not  elevated  above  the  sea,  and  in 
regions  where  the  snowfall  is  not  excessive. 

Many  of  the  hypotheses  advanced  to  account  for  the  previous  exist- 
ence of  glaciers  over  northeastern  North  America  and  over  north- 
western Europe  might  be  tested  in  the  Greenland  region  at  the  present 
day,  and  many  of  them,  if  so  tested,  it  is  safe  to  say,  would  lie  found 
wanting.  It  is  evident  that  the  more  familiar  we  become  with  existing 
glaciers  and  with  the  climatic  and  topographic  conditions  on  which  they 
depend,  including  a  study  of  the  currents  and  temperatures  of  the  adjacent 
sea,  the  better  able  we  shall  be  to  interpret  the  records  left  by  ancient 
glaciers  and  to  restore  in  fancy  the  condition  of  large  portions  of  the  earth 
now  thickly  inhabited  when  covered  by  former  ice  sheets. 

Our  knowledge  oi  the  glaciers  of  Greenland  has  been  greatly  extended 
by  observations  made  by  Prof.  T.  C.  Chamberlin  in  the  summer  of  1894, 


142 


GLACIIOliS    OF    NOKTll    A.MKUICA. 


wliile  connected  witli  the  second  Peary  relief  expedition.  The  records  ot 
the  studies  then  made  were  not  avaihahle  when  the  book  now  hefore  you 
was  written,  although  in  revising  it  several  references  to  them  have  hccu 
introduced. 

A  condensed  account  was  given  by  Chamberlin  of  his  observations  in 
(ireenland  in  the  form  of  a  presidential  acUlress  before  the  (icologiciii 
Society  of  America,  at  Baltimore,  in  I)cccmbe»  1804,  and  subsequently 
printed  in  the  bulletin  of  the  Society.^  A  much  jnore  extended  record 
has  since  been  jjublishcd  in  the  .Journal  of  (Jeology.  ^  These  reports  con- 
tain a  critical  ai:d  detailed  account  of  glacial  2)henomen,a.  Not  only  are 
the  actual  conditions  as  they  nov/  exist  in  the  portion  of  Greenland  visited 
minutely  recorded,  but  general  principles  are  discussed  that  have  a  bear- 
ing on  glacial  phenomena  in  other  regions  and  on  the  interpretation  of  the 
records  of  formerly  glaciated  countries. 

Among  the  more  interesting  results  of  these  recent  studies  is  the  con- 
firmation of  the  reports  of  previous  travelers  in  reference  to  the  character 
of  the  })recipitous  and  even  overhanging  precipices  in  which  the  glaciers 
of  the  far  north  frequently  end.  The  "  Chinese  Wall  "  described  by  Lock- 
wood  and  Hrainard,  which,  to  persons  familiar  with  glaciers  in  temperate 
latitudes  only,  a})peared  to  be  such  an  abnormal  feature,  is  shown  by  Chani- 
bcilin  to  be  chaiacteristic  of  the  manner  in  which  Arctic  glaciei-s  terminate. 
Many  of  the  photographic  illustrations  issued  in  connection  with  the 
accounts  of  recent  studies  referred  to  bring  out  this  feature  with  almost 
startling  reality.  Two  of  these  pictures,  through  the  kindness  of  Pro- 
fessor Chamberlin,  are  reproduced  on  Plate  22. 

Another  fact  of  great  interest  is  the  very  definite  stratification  of  many 
of  the  glaciers  in  the  far  north.  I)i  this  respect  the  sections  displayed  at 
the  extremities  of  the  tongues  of  ice  extending  out  from  the  central  Green- 
land sheet,  rese ml  >le  the  sections  exposed  in  the  sides  of  crevasses  in  the 
neve  regions  of  more  southern  mountains.  In  fact,  several  of  the  phases 
of  the  northern  glaciers  suggest  that  they  correspond  more  nearly  with  the 
neves  of  Alaska  and  of  Alpine  regions  generally  than  they  do  with 
''  glaciers  proper."  In  a  certain  sense  they  may  be  said  to  be  examples  of 
"arrested  development."  The  glaciers  of  the  far  north,  it  appears,  are 
frequently  as  definitely  bedded  and  as  beautifidly  laminated  as  the  best 
exanqjles  of  sedimentary  rocks.  This  resend)lance  to  rock  exposures  is 
still  farther  increased  by  the  fact  that  in  some  instances  t  e  stratified  ice 

1"  Recent  Glacial  Suidies  in  Greenland,"  Bull.  Geol.  Soc.  Am.,  vol.  0,  pp.  109-?20. 
2  Vols.  2,  3,  ami  4.  ,       .^  -  


(Ji-AC'iKiis  OF  Nonrii  Amkiiua. 


kX     • 


■^l«>f.... 


■■'•^-^^■^'■-  .Kji- 


^'S^ 


Plate  22. 


>v^^/"' 


1'  ~  ^^"S!^- 


<:V: 


Fig.    a. -FRONT   OF    BRYANT   GLACIER,   GREENLAND. 
Showing  viTtii'.il  Willi  and  .'ilriitilioulidu  of  the  ice.    (After  T.  C.  C'hiiim)erlin.) 


fi^BM^^^W^BI^^MB^^^^B^Bi^BM^B^BMBBBi^^^^^^hB^M^Mmi  Mil  V 

^g|HBHUi|H|flK^^.;  ~ 

^^^^^^^^^I^^^^^^^^^^^^^^^^^^^^^^H^^HRISk''^? 

■WIT"---       --.r 

1 

F'G.   B.  — PORTION  OF  SOUTHEAST   FACE  OF  TUKTOO  GLACIER,  GREENLAND. 
Showing  projection  of  the  upper  layers  and  the  Huting  of  their  under  surfaces.    (After  T.  C.  ChauibcrliuJ 


OLACIKIIH  I)K  NoilTII  AMKUK  A. 


I'LATi;  2-2. 


c^        A  r-o/^ki*T-      ^\  r-      rtrw/kk.iT-      /^  i    *  ^  i  r-  f^        ^  >^  ^  ^_._l-. — ^ 


GLACIEUS    IN    THE   GUEEXLAND    REGION. 


143 


is  folded  and  contorted  in  the  Uiiinner  fiXMjuently  to  bo  observed  in  gneiss 
and  schist,  and  is  also  faulted  and  overthrust.  These  structural  features 
may  be  seen  in  the  Malaspina  ice  sheet  and  in  other  glaciers  of  tenijjerate 
regions,  but  nowhere,  so  far  as  known,  on  such  a  grand  scale  or  such 
clearness  of  details  as  in  (ireenland. 

Accompanying  and  frequently  intimately  associated  with  the  marked 
stratification  of  the  (ireenland  glaciers  is  the  occurrence  of  debris  in  well- 
defined  layers.  The  scarps  at  the  extremities  of  the  glaciei-s,  as  stated  by 
Chamberlin,  "usually  present  two  great  divisions,  an  upper  trjict  of  thick, 
obscurely  laminated  layers  of  nearly  white  ice  and  a  lower  laminated  tract 
discolored  by  debris.  At  the  base  there  is  usually  a  talus  slope,  but  only 
sometimes  a  typical  moraine.  In  the  up})er  portion  bluish  solid  layers 
sei)arate  the  more  pttious  ice  into  minor  divisions,  and  these  are  grou[)ed 
by  consolidation  into  more  massive  layers.  Sometimes  the  whole  U[)i)er 
division  consists  of  a  single  stratum,  but  more  cf)mmonly  it  is  divided  into 
several  great  beds  separated  by  quite  distinct  i)lanes. 

"  The  lower  discolored  divisions  also  sometimes  consist  of  one  great 
stratum,  but  oftener  it  is  divided  into  many  thick  layers,  as  in  the  case  of 
the  white  ice  above.  Very  numerous  partings  further  divide  these  beds 
into  minor  layei-s  of  varying  thickness,  grading  down  into  delicate 
laminations,  a  dozen  or  a  score  to  an  inch." 

The  two  strongly  marked  divisions  exhibited  by  this  and  numerous 
associated  glaciers  seem  to  indicate  that  they  were  formed  separately. 
To  one  studying  the  photogiaphs  of  these  glaciers  the  marked  contrast 
between  the  upper  and  lower  portic>ns  suggests  that  the  upper  laj-ers 
of  clear  ice  have  advanced  upon  the  lower  dirt-stained  layers  after  the 
debris  they  contain  had  been  concentrated  by  melting.  The  two  divi- 
sions would  thus  represent  two  separate  stages  of  ice  advance.  As 
this  explanation  is  not  touched  upon  by  Chamberlin,  however,  it  is 
probable  that  there  are  insuperable  objections  to  it,  and  that  the  true 
reason  of  the  contrast  referred  to  is  less  obvious  and  not  fully  under- 
stood. 

After  discussing  the  various  ways  in  Avliich  glaciers  may  become  strati- 
fied, Chamberlin  summ.arized  his  conclusions  as  follows  :  "  It  would  ai)pear 
that  the  stratification  originated  in  the  inequalities  of  deposition,  emphii- 
sized  by  intercurrent  winds,  rain,  and  surface  melting  :  that  the  incipient 
stratification  may  have  been  intensified  by  the  ordinary  processes  of  con- 
solidation ;  that  shearing  of  the  strata  upon  each  other  still  further 
emphasized  the  stratification  and  developed  new  horizons  under  favorable 


r 


144 


ULACiiSUS  OF   NUKTU    AMKUICA. 


I  i 


coiiditiniiH  ;  thrt  hasal  int'(iimlitii'.s  introduced  new  jdanes  of  stniiifu-ation, 
accoini»aiiied  by  earthy  debris,  and  that  this  process  extended  itself  so 
far  as  even  to  form  very  niiuntc  laminae." 

Anotiier  phenomenon  displayed  in  a  wonderful  way  at  the  extremitij^s 
of  the  (Jreenland  ^Macier,  and  not  previously  noted  in  other  regioits,  is  the 
manner  in  which  certain  layers  jut  out  from  the  faces  of  tlu;  ice  cliffs  so  us 
to  form  projecting  cornices.  Their  appearance  is  shown  in  Fig.  B,  Platii 
22.  These  jjrojections  were  seen  on  almost  every  one  of  the  vertical  gla- 
cial faces  examined,  an<l  wtre  found  to  vary  in  width  from  a  few  inches  to 
one  or  two  feet,  and  in  rare  cases  to  reach  eight,  ten,  or  fifteen  feet.  'J'lu; 
under  surfaces  of  the  cornices  are  frequently  fluted,  as  may  be  seen  in  t}ic 
accompanying  illustration.  These  cornices  at  Hrst  sight  appear  to  be  due 
to  a  thrusting  ftaward  of  the  edge  of  an  individual  layer  beyond  the  next 
layer  below.  Movement  along  shearing  planes  seems,  then,  to  be  indicated. 
As  shown  by  Chamberlin,  however,  if  this  jjrocess  is  really  in  action,  the 
results  produced  by  it  in  the  unequal  extension  of  various  layei-s  at  the 
extremities  of  the  glaciers,  are  modified  and  masked  to  yome  extent  by 
unequal  melting.  Each  layer  of  clear  ice  which  projects  so  as  to  form  a 
cornice  usually  has  a  dark  dirt-stained  layer  below  it.  The  dark  layer 
absorbs  heat  more  ra})idly  than  the  clear  ice  and  is  consequently  melted 
back  more  rapidly.  The  fluting  on  the  under  side  of  the  cornices,  which 
it  wjis  supposed  might  be  produced  by  the  ice  being  pushed  forward  over 
stones  or  inequalities  in  the  hayer  beneath,  Avas  found  on  further  study,  to 
be  due,  to  a  considerable  extent  at  least,  to  water  which  trickled  down  the 
face  of  the  overlying  layer.  In  some  instances,  hoAvever,  the  junction 
plane  between  a  i)rojecting  layer  and  the  stratum  beneath  was  itself  found 
to  be  fluted.  This  and  other  evidence  favors  the  idea  that  planes  of  shear 
are  the  initial  cause  of  the  unequal  projection  of  various  layei-s  in  the 
terminal  escarpments.  The  development  of  such  planes  of  shear  seems  at 
first  opposed  to  the  commonly  accepted  explanation  of  the  character  of 
glacial  motion,  but  as  the  cornices  are  formed  by  the  advance  of  layers 
of  clear  ice  over  other  dark  layers,  the  shearing  planes  may  be  due  to 
unequal  rigidity  caused  by  the  debris  in  the  lower  layer,  and  thus  still  be 
in  harmony  with  the  hypothesis  that  ice  flows  as  a  plastic  solid. 

Measurements  made  by  Lieutenant  Peary,  of  the  flow  of  Bowdoin 
glacier,  in  about  latitude  77°  45',  showed  that  the  rate  during  the  month  of 
July  was  four-tenths  of  a  foot  at  the  southwest  point,  near  the  east  border, 
and  2.78  feet  at  the  farthest  point,  near  the  center,  with  an  average  of 
1.89  feet  for  the  whole. 


ULACIEUS    IN    TUB  OUKKNI.AND   UEUION. 


145 


Ore  of  the  most  interesting  of  (^liiPnlKMlin's  disioveries,  as  previonsly 
mentioned,  is  tiie  presence  of  a  small  driftlcss  area,  on  the  shore  of  Howdoin 
hay,  in  whieh  the  rocks  are  deeply  decayed.  Evidence  is  thus  furnished 
that  no  great  extension  of  ice  in  the  region  referred  tohasoccnrred  within 
re(!en^  geological  tinier.  It  is  to  he  renu'inhertjd,  however,  that  Ingelield 
gulf  is  to  the  west  and  on  the  side  of  the  great  (ireenlaiul  ice  sheet,  the 
How  of  which  is  supposed  to  he  mainly  southward.  The  tongues  of  ice 
that  c  me  down  to  the  sea,  or  approximately  to  that  level,  may  he  the 
lateral  drainage  of  the  partially  stagnant  horder  of  the  main  snow  field, 
and  conse(iuently  would  he  less  affected  hy  an  increase  in  accumulation 
than  the  secondary  glaciei-s  farther  south.* 

Since  C'hamherlin's  visit  to  (ireenhmd  in  connection  with  the  second 
Peary  relief  expedition,  a  third  expedition  of  the  same  character  visited 
that  region  in  the  sunnner  of  1895.  Prof.  11.  1).  Salishury  was  a  memher 
of  tliis  last  company,  and,  it  is  to  he  exi)ected,  will  make  many  additions 
to  the  glacial  observations  previously  obtained.  Salisbury's  reports  will 
jirohablybe  pul)lished  in  the  Bulletin  of  the  (icological  Society  of  America 
and  in  the  Journal  of  Geology. 

1  I  liave  been  led  to  make  this  su,i,'ge8tion  from  certain  occurrences  observed  in  Alaska, 
liayden  glacier,  to  the  east  of  Mount  St.  Klias,  Hows  i)ast  the  )'"ail  of  a  deep,  hi;;li-f;rade  lateral 
valley  without  sending  a  tongue  of  ice  into  it.  In  iiscending  the  lateral  valley  one  sees  in 
front  of  hini  a  wall  of  ice  ISO  or  200  feet  lugli,  formed  by  the  border  of  ilayden  glacier.  Tho 
ice  in  this  wall  is  practically  stagnant  and  protrudes  but  slightly  into  the  lateral  valley,  although 
th(  central  current  of  the  glacier  flows  past  ita  entrance  and  joins  the  Malaspina  ice  sheet  sev- 
eral miles  to  the  south.  The  conditions  there  seem  to  be  similar,  althougli  on  a  much  smaller 
scale,  to  those  found  in  the  Ingefield  region.  It  thus  appears  possible  that  a  decided  increase 
in  the  main  Greenland  ice  sheet  might  occur,  the  direction  of  tlow  being  soulliward,  without 
greatly  changing  the  conditions  in  the  lateral  ice  tongues  that  branch  oft  from  tlie  side  of  the 
main  current.  These  condilioiis  may  also  account  for  the  extreme  sluggishness  of  tho  small 
glaciers  about  Ingefield  gulf. 


CHAPTER   VIII. 

CLIMATIC   CHANGES   INDICATED  BY   THE   GLACIERS   OF 

NORTH  AMERICA.i 


It  ^as  been  shown  by  Dufor  ^  and  othei's  that  in  general  the  glaciers 
of  Eurojie  and  Asia  are  retrograding;  that  is,  their  extremities  are  ^\ith- 
drawing  farther  and  farther  up  the  valley  througli  which  they  flow.  Sim- 
ilar changes  are  known  to  be  in  progress  in  the  glaciers  of  the  southf  ni 
heinisphere,  but  ^vhether  a  general  recession  is  there  in  progress  has  not 
been  satisfactorily  determined.  The  changes  observed  in  the  glaciers  of 
Europe  and  Asia  make  it  important  to  ascertain  If  evidence  of  similar 
climatic  oscillations  can  be  obtained  from  a  study  of  the  ice  bodies  of 
North  America.  Whether  the  observed  variations  in  the  lengths  of  exist- 
ing glaciers  are  wholly  due  to  changes  in  their  climatic  environment,  or 
ai'e  influenced  to  some  extent  by  other  conditions,  will  be  briefly  con- 
sidered in  the  closing  paragraphs  of  this  chapter. 

In  the  preceding  portion  of  this  book  several  references  have  been 
miule  to  recent  changes  in  the  glacier  described.  The  bearing  of  these 
observations,  however,  on  the  study  of  the  conditions  governing  the  origin, 
growth,  and  decadence  of  glaciers,  and  on  still  wider  generalizations  in 
reference  to  the  origin  and  decline  of  glacial  epochs,  is  such  as  to  warrant 
some  repetition. 

The  evidence  thus  far  gathered  concerning  recent  changes  in  the 
glaciers  of  North  America  is  remarkably  consistent,  and  shows  that  with 
the  exception  of  a  single  glacier  in  Alaska  and  perhaps  also  of  some  of 
the  Greenland  glaciers,  they  are  all  experiencing  a  general  retreat.  It 
must  be  remembered,  however,  thac  no  precise  and  accurate  studies  in  this 
connection  have  been  made.  Almost  all  of  the  information  in  hand  is  ot 
a  qualitative  character,  obtained  for  the  most  part  incidentally  in  connec- 
tion with  other  studies.  While  the  conclusion  that  the  glaciers  are 
retreating  is  apparently  well  founded,  more   detailed  observations  will 

1  This  chapter  is  a  reprint,  with  slight  modifications,  of  a  paper  by  the  writer  in  the 
American  Geologist,  vol.  9,  1802,  pp.  ii22-ii3(\. 

a  Bull.  Soc.  Vaud.  So.  Nat.,  vol.  17,  1881.  pp.  422-426. 


m 


CLIMATIC    CHANGES. 


147 


probal>ly  show   that. this   is   accomplished   by  many   minor   osciUations 
which  may  include  periods  t>f  local  advance. 

Character  of  the  Evidenc*?.  —  Evidence  of  the  advance  or  retreat  of 
the  ends  of  alpiiie  glaciers,  or  of  the  borders  of  piedmont  and  continent  d 
glaciei-s,  may  be  obtained  ni  various  ways.  Glaciei-s  which  are  advancing 
sometimes  plow  into  the  debris  in  front  of  them  and  force  it  up  in  concen- 
tric ridges,  usually  with  the  formation  of  cracks  in  the  soil.  The  surfaces 
of  the  ridges  formed  in  this  way  are  frequently  covered  with  vegetation, 
which  in  addition  to  their  forms  and  the  character  of  the  material  of  which 
they  are  composed,  serves  to  distinguish  them  from  terminal  moraines. 
When  a  glacier  advances  into  a  forest,  the  trees  are  broken  off  and  piled 
in  confused  japs  about  the  margin  of  the  ice.  The  upper  surface  of  a 
glacier  is  known  to  flow  faster  tlian  the  ice  below,  aiid  an  advance  is  prob- 
ably aoomplished  by  the  upper  surface  flowing  over  and  burying  the  ice 
which  rests  on  the  ground.  For  this  reason  advancing  glaciers  usually 
present  bold  scarps  at  their  extremities,  and  in  general,  are  not  covered 
witli  a  broad  shee^  of  debris. 

\n  retreating  glaciers  the  layei-s  of  new  snow  deposited  on  the  n6v6 
fields  and  changing  to  ice  as  they  flow  downward  are  melted  before  reach- 
ing the  end  of  the  ice  streams,  and  the  slow-moving  ice  at  the  bottom  is 
thus  left  exposed  and  melts  away.  The  retreat  is  accomplished  not  by  a 
contraction  of  the  ice  body,  but  by  the  melting  of  its  distal  extremity. 
The  ice  which  is  not  covered  by  the  advance  of  fresh  layei^s,  melts  at  the 
surface,  and  the  englacial  debris  is  concentrated  at  the  surface.  When 
a  sheet  of  debris  of  this  character  is  extensive  and  cover's  the  lower 
portion  of  a  glacier  from  side  to  side,  it  indicates  that  the  ice  beneath  is 
practically  stationary  and  consequently  is  melting  and  retreating.  The 
ends  of  retreating  glaciers  frequently  have  a  gentle  surface  slope,  and  in 
many  instances  are  so  completely  concealed  by  debris  that  the  actual  ter- 
minus of  the  ice  cannot  be  distinguished.  When  the  moraines  are  heavy, 
however,  and  espe(ially  when  they  are  clothed  with  vegetation,  the  melt 
ing  of  the  ice  beneath  is  greatly  retarded,  and  in  some  observed  instances 
the  glaciers  thus  protected  terminate  in  bold  scarps. 

When  the  end  of  a  glacier  recedes  more  rapidly  than  soil  can  form  on 
the  abandoned  area,  so  as  to  admit  of  the  growth  of  plants,  a  desolate 
tract  is  left  about  its  end,  on  which  concentric  lines  of  stones  and  boulders 
may  indicate  halts  in  the  retreat.  Barren  areas  of  this  nature,  when  the 
lack  of  vegetation  is  not  due  to  the  action  of  watt  •  from  the  ice,  are  good 


148 


GLACIERS    OF    NORTH   AMERICA. 


evidence  of  recent  glacial  recession.  When  glaciers.which  flow  tiirough  a 
valley  having  steep  sides,  become  stagnant,  a  general  lowering  of  the  sur- 
face, decreasing  up  stream,  takes  place,  which  leaves  the  bordering  slopt.-* 
bare  of  vegetation.  The  action  of  rain  and  rills  on  such  surfaces  may 
indicate  to  some  extent  the  length  of  time  they  have  been  exposed.  The 
presence  of  fine  glacial  debris  on  slopes  from  which  it  would  be  easily 
washed  by  rain  may  also  furnish  evidence  in  the  same  connection.  Retreat- 
ing glaciers  sometimes  leave  detached  masses  of  ice  which  are  melted  in 
the  course  of  a  few  yeai-s,  and  hence  when  present  indicate  rapid  changes. 
The  amount  of  sulKierial  ei'osion  on  glaciated  areas  may  also  serve  to 
indicate  the  length  of  time  they  have  been  exposed. 

These  various  classes  of  evidence  usually  enable  one  to  determine  defi- 
nitely whether  a  glacier  has  recently  advancet'  or  retreated,  and  may  some- 
times afford  a  clu..  to  the  rate  of  these  changes.  When  an  opportunity  is 
afforded  for  detailed  study,  various  surveying  and  photographic  methods 
may  be  employed.  If  observations  can  be  continued  season  after  season, 
the  limits  of  a  glacier  at  various  times  maybe  recorded  by  monuments,  by 
marking  the  position  of  its  margin  with  asphaltum,etc.  Instructions  in  this 
connection  have  been  published  by  Prof.  H.  F.  Reid.^  In  the  study  of  tlie 
glaciers  of  America  we  have,  with  the  exception  of  Muir  glacier,  no  defi- 
nite quantitative  measurements,  and  must  rely  on  such  phenomena  as  have 
been  indicated. 

California.  —  Some  of  the  small  glaciers  in  the  High  Sierra,  as  already 
described,  have  barren  areas  about  their  extremities,  showing  that  they 
are  slowly  receding.  No  measure  of  the  rate  of  this  recession  has  been 
attempted. 

Observations  by  J.  S.  Diller,  of  the  United  States  Geological  Survey, 
on  Mt.  Shasta  indicate  that  the  glaciers  in  northern  California,  like  those 
farther  south,  are  retreating.  Evidence  of  this  is  furnished  by  barren 
areas  about  the  ends  of  several  of  the  glaciers  and  by  a  conspicuous  lateral 
moraine  on  the  side  of  the  Whitney  glacier,  which  in  1887,  was  about 
twenty-five  feet  above  the  level  of  the  adjacent  ice. 


m 

"11 

it 


Oregon  and  Washington.  —  The  glaciers  on  the  Cascade  mountains 
have  been  visited  by  a  number  ot  persons,  but  I  have  been  unable  to 

»"The  ^a^iation9  of  Glaciera,"  Journal  of  Geology,  vol.  3,  1895,  pp.  278-288.  This 
paper  contains  references  to  other  puulications  in  which  methods  of  observing  changes  in 
glaciers  are  described. 


CLIMATIC    CHAN'GEH. 


149 


obtain  satisfactory  evidence  of  advance  or  recession.  An  inspection  of 
photograplis  of  the  glaciers  on  Mount  Rainier  indicates  tliat  they  end  in 
areas  bare  of  vegetation,  which  presumably  were  recently  occui)ied  by 
ice. 


BritiHh  Columbia.  —  The  glaciei-s  of  British  Columbia,  altliougli 
numerous  and  important,  are  but  imperfectly  known,  and  only  a  few 
observations  on  recent  changes  have  been  made.  Many  of  these  glaciers, 
however,  have  been  seen  by  Dr.  G.  M.  Dawson,  who  informs  me  that  in 
no  instance  are  there  evidences  that  they  have  recently  advanced,  and  that 
he  consider  it  safe  to  assume  that  they  are  either  stationary  or  slowly 
receding. 

R.  G.  McConnel,  of  the  Canadian  Geological  Survey,  has  kindly 
informed  me  that  the  glaciei's,  both  on  tlie  Stikine  river  and  in  the 
Rocky  mountains,  have  shrunken  back  from  fresh-looking  moraines,  and 
that  the  intervals  between  the  ice  and  the  moraines,  in  all  instances 
examined  by  him,  were  destitute  of  trees  and  contained  but  little  vege- 
tation of  any  kind.  In  his  opinion  a  marked  retreat  has  occurred  within 
the  last  century  or  two,  but  whether  it  has  been  in  progress  during 
the  past  one  or  two  decades  cannot  l)e  decided  from  the  evidence  in 
hand.  Observations  made  by  Macoun  and  Ingei"soll  confirm  this  con- 
clusion.^ 

The  Illecellewaet  glacier  at  Glacier  station,  on  the  Canadian  Pacific 
Railroad,  in  the  spring  of  1891,  was  bordered  by  a  bavren  area,  between 
the  ice  and  the  encircling  forest,  several  hundred  yards  in  breadth,  which 
had  evidently  been  but  recently  abandoned  by  the  glacier.  A  small 
moraine  on  the  western  side  of  the  glacier  also  suggested  a  recent  shrink- 
ing of  the  ice.  The  evidence  of  a  recent  retreat  of  this  glacier  hsis  also 
been  noted  by  W.  S.  Green.^ 

An  absence  of  vegetation  al)out  the  extremity  of  one  of  the  glaciers  on 
Stikine  river  was  noted  by  Blake,^  and  may  probably  be  taken  as  an  indi- 
cation of  a  recent  retreat  of  the  ice.  A  legend  current  among  the  Stikine 
Indians  indicates  that  two  glaciere  on  opposite  sides  of  the  stream  were 
formerly  united  and  that  the  river  then  flowed  through  a  tunnel  beneath 
the  ice. 


^"Mountaineering  in  British  Columbia,"  by  Ernest  Ingersoll,  Bull.  Am.  Geog.  Soc, 
vol.  18,  1880,  p.  18. 

2  "Among  the  Selkirk  Glaciers,"  London,  18iK),  p.  09. 
'  American  Journal  of  Science,  vol.  44,  1 307,  pp.  90-101. 


150 


GLACIERS   OF   NOUTH   AMERICA. 


Alaska.  —  The  evidence  that  a  general  retreat  of  the  glaciers  of  Alaska 
is  still  in  progress  is  abundant,  and  in  a  few  instances  is  of  quantitative 
value. 

* 

Lynn  Canal.  —  About  this  magnificent  inlet,  as  previously  described, 
there  are  many  ice  streams  of  the  alpine  type,  which  descend  nearly  to  sea 
level,  but  none  of  them  are  now  actually  tide-water  glaciers.  About  the; 
ends  of  many  of  them  there  are  dense  forests  of  spruce  trees  which  musl 
have  been  growing  for  at  least  one  hundred  and  fifty  years,  but  between 
the  forests  and  the  present  terminu.s  cf  the  ice  there  is,  in  several  instances, 
a  barren  area  covered  with  morainal  and  alluvial  deposits  and  bearing  every 
indication  of  having  but  recently  been  abandoned  by  the  glaciers.^  These 
conditions  are  especially  noticeable  at  the  extremity  of  the  Davidson 
glacier.  Between  the  present  terminus  of  the  ice  and  the  encircling  foresi 
there  is  a  barren  tract  half  a  mile  broad,  which  has  been  left  by  a  retreat 
of  the  ice  so  recently  that  vegetation  has  not  been  able  to  take  root  upon 
it.  A  decided  retreat  of  the  ice  has  here  recently  occurred,  and  to  all 
appearances  is  still  in  progress,  but  no  observations  of  its  rate  have  been 
made. 

Conditions  similar  to  those  seen  at  Davidson  glacier  were  observed  in 
connection  with  several  otlier  ice  streams  in  the  same  region.  In  Taku 
inlet,  the  Norris  gl.acier  comes  down  to  sea  level,  but  is  separated  from  the 
water  by  broad  mud  flats.  There  is  no  indication  that  this  glacier  has 
recently  advanced,  and  an  accumulation  of  debris  over  its  surface  and 
about  its  extremity  indicates  that  it  is  melting  away-  The  Taku  glacier, 
near  at  hand,  is  of  the  tide-water  type ;  and  evidence  of  recent  changes  in 
the  position  of  its  terminus  is  wanting. 

Glacier  Bay.  —  The  evidence  of  recent  changes  in  Muir  glacier  has 
been  presented  by  Professor  Wright,'^  who  has  shown  that  it  has  quitt' 
recently  been  both  more  extensive  and  of  less  size  than  at  present.  Ad(U- 
tional  evidence  of  these  changes  has  been  supplied  by  Reid,^  who  con- 
cludes that  Muir  glacier  and  other  ice  streams  now  discharging  into  Glacier 
bay,  were  formerly  much  more  extensive  than  at  present,  and  at  the  time 
of  Vancouver's  expedition,  in  1794,  probably  occupied  the  whole  of  the 


1  Bull.  Geol.  Soc.  Am.,  vol.  1,  1890,  p.  152. 

2  "  The  Ice  Age  in  North  America,"  by  G.  Frederick  Wright,  Few  York,  1889,  pp.  61-&7. 
*  "  Studies  of  the  Muir  Glacier,"  by  H.  F,  Reid,  in  National  Geographic  Magazine,  vol. 

4,  1891,  pp.  34-12. 


CLIMATIC    CHANGES. 


151 


bay  to  a  point  some  distance  below  Willoughby  island.  The  retreat 
during  one  hundred  years  is  thought  to  l>e  in  the  neighl>orhood  of  fourteen 
miles.  This  conclusion,  however,  rests  on  certain  passages  in  the  narrative 
of  Vancouver's  voyage,^  which  may  possibly  reter  to  floating  ice,  and  not 
to  actual  glaciere,  and  therefore  do  not  have  the  quantitative  value  indi- 
cated above.  But  under  any  plausible  rendering  of  Vancouver's  account 
it  does  not  seem  possible  to  escape  the  conclusion  that  the  ice  in  Glacier 
Day  was  far  more  abundant  at  the  time  of  his  visit  than  in  recent  yeai-s. 

Observations  made  by  Wright  and  Keid  in  1886  and  1890,  respectively, 
show  that  Muir  glacier  has  retreated  during  this  interval  more  than  1000 
yards.  This  observed  rate  of  recession  would,  if  continuous  for  one  hun- 
dred years,  produce  a  retreat  of  approximately  fifteen  miles,  and  affords 
ground  for  believing  that  the  great  retreat  supposed  to  have  occurred  since 
Vancouver's  visit  is  approximately  correct. 

John  Muir  has  kindly  contributed  the  following  note  concerning  the 
retreat  of  the  glaciers  of  southeastern  Alaska,  which  conrirms  the  evidence 
^  already  presented : 

"  All  the  glaciere  that  have  come  under  my  observation  in  southeastern 
Alaska  have  retreated  and  shallowed  since  first  I  became  acquainted  with 
them  in  1879  and  1880.  Those  in  which  the  declivity  of  the  channels  is 
least  have  of  course  receded  the  most.  During  the  ten  years  between 
1880  and  1890,  Muir  glacier  has  receded  about  one  mile,  at  its  mouth  in 
Muir  inlet." 


St.  Ellas  Region.  —  Much  space  could  be  occupied  in  recording  obser- 
vations which  indicate  a  general  recession  of  the  glaciere  about  Yakutat 
and  Disenchantment  bays  and  along  the  adjacent  ocean  shore,  but  a  brief 
summary  of  this  evidence  is  all  that  seems  necessary  at  this  time. 

The  lower  portions  of  a  large  number  of  glaciera  in  this  region  are 
completely  covered  by  continuous  sheets  of  debris  which  has  been  concen- 
trated at  the  surface  through  the  melting  of  the  ice.  This  debris  is  not 
being  carried  forward  and  deposited  in  terminal  moraines,  but  i^;  distributed 
over  the  surface  of  the  ice  in  a  thin  sheet,  and  marks  the  stagnant  condi- 
tion of  the  glaciers  on  which  it  rests.  In  several  instances,  especially  on 
the  outer  border  of  the  Malaspina  glacier,  the  moraines  resting  on  the  ice 
are  clothed  v/ith  vegetation,  which  over  many  square  miles  forms  a  dense 
forest,  composed  principally  of  spruce  trees,  some  of  which  are  three  feet 

1  "Voyage  of  Discovery  around  the  World,"  by  Vancouver,  vol.  5,  pp.  420-423.  Quoted 
by  Wright  in  "  Ice  Age  of  North  America,"  pp.  66-67. 


152 


GLACIERS   OF   NORTH   AMERICA. 


ill  diameter.  Within  the  forest-covered  border  and  forming  a  belt  concen- 
tric with  it  there  is  a  barren  tract  covered  with  stones  and  bouklers.  The 
forests  growing  on  the  glacier  and  also  thousands  of  lakelets,  both  in  the 
outer  border  of  the  barren  moraine  and  in  the  adjacent  forest-covered 
moraine,  indicate  conclusively  that  the  ice  sheet  is  stagnant  and  conse- 
quently wasting  away.  On  the  coast  bordering  the  Malaspina  glacier  on 
the  south,  there  were  formerly  two  projections  called  Point  Rio  and  Cape 
Sitkagi,  which  were  noted,  by  the  explorei-s  one  hundred  years  ago.  In 
traversing  this  coast  in  1891  I  found  that  no  capes  exist  at  the  localities 
referred  to.  At  the  site  of  Cape  Sitkagi  there  is  evidence  that  the  sea 
has  recently  invaded  the  j^lacial  boundary.  On  the  sides  of  many  of  the 
alpine  glaciei's  in  the  adjacent  mountains  there  are  steep  slopes  bare  of 
vegetation  although  well  below  the  upper  limit  of  tree  growth  on  adjacent 
areas,  which  indicate  that  the  ice  streams  have  recently  shrunken  within 
their  beds.  My  conclusion  after  two  visits  to  the  glaciers  in  the  St.  Elias 
region  is  that  without  exception  they  are  rapidly  retreating. 

Near  Point  Manby  there  is  a  locality  where  the  Malaspina  glacier  has  . 
recently  advanced  about  1500  feet  into  a  dense  spruce  forest,  cutting  off 
the  trees  and  sweeping  them  into  confused  heaps.  After  advancing  the 
ice  retreated,  leaving  a  typical  morainal  surface  covered  with  lakelets. 
This  is  the  only  instance  of  a  recent  advance  that  has  come  under 
my  notice  in  Alaska. 

The  head  of  Yakutat  bay  was  visited  by  Malaspina  in  1791,  and  again 
by  Captain  Puget  in  1794.  Each  of  these  explorers  found  the  inlet 
blocked  by  a  wall  of  ice  from  shore  to  shore.  No  other  observations  in 
this  connection  were  made  until  my  visit  in  the  summer  of  1890.^  From 
what  may  now  be  observed  it  is  evident  that  the  Turner  and  Hubbard 
glaciers,  which  come  down  to  the  water  at  the  head  of  the  inlet  and  break 
off  in  bergs,  must  have  extended  some  five  or  six  miles  beyond  their 
present  position  at  the  time  of  Malaspina's  and  Puget's  visits,  and  were 
then  united  so  as  to  completely  block  the  entrance  to  Disenchantment  bay, 
which  is  a  continuation  of  Yakutat  bay.  These  observations  show  conclu- 
sively that  the  gl.aciei-s  mentioned  have  retreated  five  or  six  miles  within 
the  past  one  hundred  years.  The  small  recession  that  has  here  taken 
place,  in  comparison  with  the  changes  reported  in  Glacier  bay,  during  the 
same  time,  is  probably  due  co  the  fact  that  the  n^v^  from  which  Muir 


1  Map  indicating  the  position  of  the  ice  in  1791  is  shown  on  Plate  7,  and  its  extent  in 
1800  on  Plate  8,  of  my  "  Report  on  an  Expedition  to  Mount  St.  Elias,"  in  National  Geograpliic 
Magazine,  vol.  3. 


CLIMATIC    CHANGES. 


153 


glacier  flows  is  much  lower  than  the  snow  fields  drained  by  the  Hul/bard 
and  Turner  glaciers,  and  presumably  more  sensitive  to  climatic  changes. 


«li 


North  Side  of  tlie  St.  Elias  Mountains.  —  Dr.  C.  Willard  Hayes,  of 
the  United  States  Geological  Survey,  in  crossing  from  Selkirk  house  on 
the  Yukon  river  to  Copper  river  in  1891,  passed  for  a  portion  of  the  way 
along  the  northern  border  of  the  great  system  of  mountains  which  culmi- 
nates in  Mount  Logan  and  Mount  St.  Elias,  and  discovered  several  large 
glaciers  of  the  alpine  type  flowing  northward  from  the  neve  field  north  of 
Mount  St.  Elias.  and  also  other  glaciers  draining  ueve  fields  about  Mount 
Wrangell  and  flowing  southward.  Respecting  the  evidence  of  recent 
changes  in  these  glaciers,  Dr.  Hayes  has  kindly  supplied  the  following  r.otes: 

"  Two  large  glaciei-s  and  many  small  ones  were  seen  flowing  from  the 
St.  Elias  mountains  northward  into  the  White  Fiver  basin.  Another  flows 
from  the  southeast  into  the  pass  and  drains  into  both  the  White  and  Copper 
River  basins.  About  'e  head  of  the  Nizzenah  are  four  large  and  many 
small  glaciers.  Flowing  into  Copper  river  from  the  coast  range  are  four 
or  five  glaciers,  one  of  them  —  Miles  glacier  —  being  larger  than  any  seen 
further  in  the  interior.  Observations  were  thus  made  on  twelve  glaciers, 
and,  with  one  exception  to  be  described  later,  all  show  a  more  or  less 
rapid  recession.  The  evidence  of  this  recession  in  most  cases  is  the  accu- 
mulated moraine  covering  the  terminal  edge  of  the  glacier  ;  or  where 
there  is  not  sufficient  englacial  drift  to  accumulate  and  form  a  protective 
mantle,  the  stagnant  ice  melting  to  a  feather  edge.  The  White  River  lobe 
of  Russell  glacier  is  of  the  moraine-covered  type,  while  the  Nizzenah 
Icbc  lias  the  feather  edge.  On  the  Klutlau  and  Russell  glaciers  the  outer 
portion  of  the  moraine-covered  ice  supports  a  dense  vegetation,  which 
becomes  gradually  more  scanty  and  disappears  about  half  a  mile  from,  the 
edge  of  the  ice.  The  'cession  of  the  smaller  glaciers  along  the  Nizzenah 
appears  to  have  been  more  rajjid  than  the  advance  of  the  vegetation,  so 
that  between  it  and  the  ice  there  is  a  belt  of  bare  moraine. 

"  Miles  glacier  terminates  in  an  ice  clifl:  fronting  upon  Copper  river, 
and  the  river  has  as  yet  cut  only  part  way  through  the  dam  formed  by  the 
northern  lateral  moraine.  This  moraine  must,  until  very  recently,  ht.ve 
been  backed  up  by  the  glacier  itself,  though  the  front  of  the  latter  has 
now  retreated  two  miles  to  the  eastward. 

"  While  the  fact  of  recession  is  manifest,  the  rate  is  more  difiicult  to 
determine.  In  one  case,  however,  it  is  possible  to  connect  the  amount  of 
recession  with  an  important  episode  in  the  history  of  the  region,  namely, 


154 


GLACIERS    OF   NORTH    AMERICA. 


the  eruption  of  a  widespread  deposit  of  volcanic  ash  wliiih  extends  from 
near  the  head  of  the  Pelly  westward  to  Scolai  pass.  With  regard  to  the 
age  of  tliis  deposit  Dr.  Dawson  says  :  ^  '  While  the  erui)ti()n  mnst  have 
happened  at  least  several  hundred  yeai*s  ago,  it  can  scarcely  l)e  sup[)ost'(l 
to  have  taken  place  nu)re  than  a  thousand  years  hefore  the  })resent  time.' 

"  For  a  distance  of  about  three  miles  in  front  of  the  Klutlan  glacier 
there  is  a  deposit  of  moraine  material  perhaps  200  feet  thick,  com[)osed  of 
volcanic  ash  and  angular  rock  fragments.  This  evidently  fixes  the  position 
of  the  glacial  front  at  the  time  of  the  volcanic  erui)tion,  and  the  amount 
of  recession  since  that  e-vent.  It  is  interesting  to  note  that  on  the  present 
glacier  surface  the  volcanic  sish  is  found  only  a  short  distance  from  the  end, 
showing  that  since  the  eruption,  while  the  front  of  the  glacier  has  receded 
about  three  miles,  nearly  the  whole  mass  of  the  glacier  has  been  renewed 
by  fresh  addition  from  its  source. 

"  The  single  exceptional  case  already  referred  to  is  the  Frederika  glii- 
cier,  which  seems  to  be  advancing  its  front  instead  of  retreating.  It  has 
its  source  in  the  lagh  mountains  forming  the  eastern  membei-s  of  the 
Wrangell  group,  and  flows  south  in  a  lateral  valley,  joining  the  valley  of 
the  Nizzenah  at  right  angles.  The  front  of  the  glacier  is  parallel  with  the 
river  and  about  three-fourths  of  a  mile  from  it,  the  intervening  space  being 
a  gravel  plain.  The  glacier  terminates  in  nearly  a  vertical  ice  cliff  about 
250  fecL  high.  It  is  slightly  convex,  and  stretches  entirely  across  the 
valley,  about  a  mile  in  length.  The  surface  of  the  glacier  is  free  from 
moraines,  but  is  extremely  rough  and  broken,  unlike  the  ordinary  surface 
of  stagnant  ice  at  the  end  of  a  retreating  glacier.  At  the  foot  of  the  cliff 
is  a  small  accumulation  of  gravel  and  fragments  of  ice,  probably  pushed 
along  by  the  advancing  mass.'^ 

"An  explanation  of  this  anomalous  case  is  suggested.  Ten  miles  to 
the  westward  of  the  Frederika  another  much  larger  glacier  flows  into  the 
valley  of  the  Nizzenah.  This  is  formed  by  the  union  of  three  separate 
streams,  and  of  these  the  eastern  appears  to  be  retreating  much  nioic 
rapidly  than  either  of  the  others.  But  this  eastern  branch  probably  has 
its  source  in  the  same  basin  as  the  Frederika  glacier,  and  it  seems  not 
impossible  that  by  some  means  the  drainage  has  been  diverted  from  the 
western  to  the  eastern  outlet,  thus  causing  the  rapid  retreat  in  the  former 
glacier  and  advance  in  the  latter." 

1  Report  on  Yukon  District,  p.  46,  B. 

2  Tliis  is  the  only  authentic  instance  of  an  advancing  glacier  known  on  the  west  coast  of 
North  America.     I.  C.  R. 


mm 


CLIMATIC    CHANGES. 


155 


Cireenlaiul.  —  Kefjfiinling  recent  changes  in  the  ice  sheet  of  Greenhind 
there  is  but  scanty  evidence,  and  such  observations  as  have  lx;en  made  on 
the  advance  and  retreat  of  the  margin  of  tlie  ice  are  conflicting.  Holts 
found  in  1880,  between  hititude  01°  and  <J5°  30',  on  tlie  west  coast,  accord- 
ing to  Lindahl,^  that  "  the  border  of  the  ice  ajjpeared  to  have  retreated 
quite  recently  in  niany  j)laces  ;  in  othei's,  it  had  decidedly  advanced." 
Nansen'^  remarks  in  this  connection  that  we  cannot  even  conjecture  what 
the  present  conditions  are,  and  thinks  that  the  ol)servations  show  that 
there  is  no  strong  tendency  either  toward  advance  or  retreat.  Warren 
Upham,^  Avho  has  recently  reviewed  the  literature  relating  to  the  (ireen- 
land  ice  sheet,  informs  me  that  in  his  judgment  the  ice  is  now  slightly 
increasing  in  thickness  and  generally  .  extent.  This  conclusion  rests 
largely  on  the  general  absence  of  debris  on  the  borders  of  the  ice  sheet. 
His  studies  have  also  led  him  to  the  conclusion  that  Greenland,  in  common 
Avith  other  portions  of  the  northeast  border  of  this  continent,  is  now  having 
an  api)reciable  increase  in  cold. 

The  observations  of  those  Avho  have  traversed  the  inland  ice  agree  in 
showing  that  nearly  its  entire  surface  is  in  the  condition  of  a  ndve,  and 
suggest  that  growth  and  not  retreat  must  be  in  progress.  The  absence  of 
debris  on  the  borders  of  the  ice  sheet  referred  to  by  Upham,  is  important 
in  this  connection,  and  seems  to  indicate  that  no  great  waste  of  ice  occurs 
before  it  is  discharged  into  the  sea.  So  far  as  one  may  judge  from  the 
observations  of  others,  it  seems  as  if  the  evidence  available  i)oints  to  an 
increase  of  the  ice  sheet,  as  sui)posed  by  Upham ;  but  the  accuracy  of  this 
conclusion  is  questionable,  and  Dufor,  in  a  paper  cited  in  the  beginning 
of  this  chapter,  is  inclined  to  the  opposite  opinion.  He  states  that  in  1880, 
he  made  a  communication  on  the  retreat  of  the  glaciers  of  Europe  and 
Asia  before  a  scientific  congress  at  Reims,  and  that,  during  the  discussion 
which  followed,  one  of  the  persons  present  who  had  l)een  in  Greenland 
several  times  mentioned  that  he  "  had  noticed  that  the  glaciers  of  that  land 
had  also  retreated  considerably."  It  is  known  that  the  glaciers  of  Green- 
land were  much  more  extensive  during  a  former  epoch  than  at  present, 
and  left  records  at  an  elevation  of  3000  feet  above  the  present  ice  surface.* 

1  American  Naturalist,  vol.  22,  1888,  p.  59.3. 

2  "  First  Crossing  of  Greenland,"  vol.  2,  p.  491. 

*  The  conclusions  of  Mr.  Upham  are  also  contained  in  the  following  papers  :  "  On  the 
Cause  of  the  Cold  of  the  Glacial  Epoch,"  American  Geologist,  vol.  6,  18JK),  p.  .3.36  ;  and  "The 
Ice  Sheet  of  Greenland,"  American  Geologist,  vol.  8, 1891,  p.  150  ;  "  Criteria  of  Englacial  and 
>Subglacial  Drift,"  American  Geologist,  vol.  8,  1891,  p.  385. 

*  American  Journal  of  Science,  Third  Series,  vol.  24,  pp.  100,  101. 


rr 


150 


GLACIERS   OF   NORTH    AMERICA. 


It  may  be  .suggested  that  the  observations  referred  to  by  Dufor  possibly 
rehito  to  these  ancient  records. 


I 


i 


\V«'lglit  of  tlio  Evidence.  —  The  observations  suninuirized  in  ihis 
chapter  in  reference  to  the  Cordilleran  region,  altliough  unsatisfactory  in 
many  ways,  indicate,  with  a  single  exception  which  seems  to  have  a  special 
explanation,  that  the  ice  bodies  in  tliat  region  are  retreating.  This  con- 
clusion not  only  rests  on  direct  observations  of  several  individuals,  but  is 
sustained  by  negative  evidenca  as  well.  An  advance  of  a  glacier,  espe- 
cially in  a  forested  country,  is' apt  to  be  strongly  marked,  and  would  attrait 
the  attention  of  even  a  ciisual  observer ;  but  in  no  instance,  with  the  excc})- 
tion  reported  by  Dr.  Hjiyes,  and  the  slight  extension  on  the  border  of  the 
Malaspina  glacier  already  mentioned,  has  a  recent  advance  been  reported. 

The  fact  that  the  glaciers  at  the  head  of  Yakutat  bay  have  retreated 
several  miles  within  the  past  one  hundred  yeai-s,  as  well  as  the  still  greater 
recession  of  the  glaciers  of  Glacier  bay  during  the  same  period,  indicates 
that  the  present  general  recession  of  the  glaciei"s  of  the  Pacific  coast  has 
probably  been  in  i)rogress  for  more  than  a  century.  During  tliis  time  there 
must  have  been  many  minor  oscillations  which  our  imperfect  observations 
do  not  detect,  but  the  conclusion  that  the  general  movement  has  been 
backward  is  well  sustained. 

Theoretical  Considerations. 

The  variations  that  glaciers  are  undergoing  have  received  special  atten- 
tion during  the  past  few  years.  A  large  body  of  evidence  in  this  connection 
is  being  collected,  especially  by  members  of  various  Alpine  clubs,  but  as 
yet  these  studies  have  been  confined  principall}'  to  the  glaciei-s  of  Europe. 
The  importance  of  this  inquiry  led  the  International  Congress  of  Geolo- 
gists, at  its  meeting  at  Zurich  in  1894,  to  appoint  a  committee  for  tlie 
special  purpose  of  collecting  data  all  over  the  world,  with  the  view,  if  pos- 
sible, of  discovering  a  relation  between  the  variations  of  glaciere  and 
meteorological  phenomena.^  An  attempt  to  discuss  systematically  the 
observations  thus  far  recorded  in  this  connection  would  be  out  of  place  ut 
the  present  time,  since  no  detailed  studies  have  been  nade. of  American  gla- 
ciers ;  but  a  few  suggestions  in  reference  to  the  directions  in  which  this 
investigation  seems  to  point  may  be  of  interest  to  the  reader. 

All  the  explanations  of  the  observed  variations  in  the  length  of  gla- 
ciers thus  far  offered  are  based  on  the  supposition  that  they  are  due  to 

1  H.  F.  Reid,  "  Variations  of  Glaciers,"  Journal  of  Geology,  vol.  3,  1895,  pp.  278-288. 


CLIMATIC    CHANOKS. 


167 


climatic  changes.  In  resjiect  to  the  greater  oscilhitions  it  seems  as  if  no 
other  (ionclusiou  coiiM  Ihj  expected,  hut  minor  changes,  as  I  shall  attempt 
to  show,  may  he  due  to  other  conditions. 

Tile  statement  made  in  the  opening  paragrai)h  of  tlie  present  chapter, 
to  tlie  etl'eet  that  the  glaci  VH  of  Europe  and  Asia  are  retreating,  is  perhaps 
misleading,  as  it  refers  to  liie  algebraic  sum  of  advances  and  retreats  dur- 
ing a  term  of  years.  VVitliin  the  cycle  referred  to  there  have  undoubtedly 
been  many  minor  fluctuations  which  vary  not  only  in  amount  but  in  (Urec- 
tion,  in  different  glaciers.  In  several  instances,  certain  membei-s  of  a  group 
of  glaciers  have  advanced  during  recent  years,  — '^ile  othei-s  in  the  same 
group  have  remained  stationary  or  retreated,  and  vice  versa.  Opposite 
movements  in  ghiciers  which  so  far  as  one  can  judge  are  exposed  to  the 
same  climatic  changes  have  not  been  satisfactorily  explained. 

Changes  in  the  length  of  a  glacier  may  evidently  result  frcmi  (1)  vari- 
ations in  the  amount  of  snow  sui)plied  to  its  neve  region,  (2)  to  changes  in 
tlie  rate  of  melting,  or  (3)  to  fluctuations  in  the  rate  of  flow. 

Variations  in  the  amount  of  snow  added  to  the  n^ve  of  a  glacier,  as 
shown  in  part  at  least  by  Professor  Forel,^  may  be  considered  as  of  the 
nature  of  a  pulsation  which  is  propagated  throughout  its  length.  I'he 
end  of  a  glacier  might  therefore  alternately  advance  and  retreat  in  sym- 
patliy  with  vnriations  in  snowfall  that  occurred  scores  of  yeai-s  and  even 
centuries  before.  Two  glaciers  subject  to  the  same  climatic  conditions, 
but  of  unequal  leilgth,  or  of  the  same  length  but  having  different  mean 
velocities,  would  advance  or  retreat  at  different  periods  for  the  reason  that 
the  time  required  for  the  increment  produced  by  an  increase  of  snowfall 
to  reach  their  extremities  would  be  different.'^ 

It  has  been  suggested  that  variations  in  the  rate  of  melting  might  be 
a  factor  causing  the  ends  of  glaciers  to  advance  or  retreat.  But  as  loss 
by  melting  is  greatest  at  the  lower  extremity  of  a  glacier,  similar  effects 
would  be  expected  in  neighboring  instances,  although  alpine  glaciers  that 

»  Bibliot.  Univ.  de  Genfeve,  1881. 

2  Another  explanation  dependent  on  variations  in  snowfall  has  been  suggested  by  I'ro- 
fessor  Kichter,  who,  as  stated  by  Reid  (.lournal  of  Geology,  vol.  .3,  p.  281),  "thinks  that  the 
.accumulation  of  snow  in  the  n^v6  region,  even  under  uniform  nieteorological  conditions,  would 
in  time  produce  a  great  enough  pressure  to  overcome  the  resistance,  due  to  the  friction  against 
its  bed,  of  the  glacier's  tongue,  which  is  then  pushed  forward  with  a  greater  velocity,  result- 
ing in  the  advance  of  the  glacier  ;  this  continues  until  the  drain  on  the  n6v^  region,  on  account 
of  more  rapid  flow,  exhausts  the  accumulation  of  snow  ;  after  this  the  motion  almost  entirely 
ceases,  and  the  glacier  melts  back  until  another  advance  begins.  I'rofessor  Forel  calls  this 
the  '  theory  of  intermittent  flow,'  and  points  out  that  according  to  it  variations  in  the  size 
of  glaciers  would  be  entirely  independent  of  meteorological  changes." 


158 


OLACIEU8  OP   NORTH    AMERICA. 


descend  into  different  valleyx  mij^ht  perhaps  Ix;  influenced  differently.  It 
is  unnecessary  to  discuss  this  surrgostion,  however,  since  oliservation  on 
meteorological  changes  and  on  the  variations  of  glaciei-s  in  the  same  region 
do  not  sustain  it. 

While  it  is  customary  to  refer  the  advances  and  retreats  ohserved  in 
glaciers  to  climatic  changes,  and  although  opposite  movements  in  glaciers 
exposed  to  the  same  meteorological  conditions  may,  perhaps,  as  shown 
above,  be  explained  in  this  way  ;  yet  I  venture  to  suggest  that  there  is  a 
principle  involved  in  the  behavior  of  glacici-s  themselves  that  might  bring 
about  analogous  results.  I  refer  to  the  influence  of  debris  on  the  flo\v  of 
ice  containing  it. 

As  is  well  known,  a  concentration  of  debris  takes  place  at  the  end  of 
a  glacier,  especially  when  it  is  slowly  retreating.  This  is  due  to  the  fact 
that  while  the  volume  of  the  ice  decreases,  the  amount  of  debris  it  con- 
tains remains  practically  the  same.  The  percentage  of  foreign  material  in 
a  given  volume  of  ice  is  thus  increased.  The  rate  of  flow  of  ice,  however, 
other  conditions  remaining  the  same,  decreases  as  the  percentage  of 
contained  debris  increasts.^ 

As  the  percentage  of  debris  in  the  extremity  of  a  glacier  increases,  the 
flow  of  the  ice  will  slacken,  and  when  the  concentration  reaches  a  certain 
point,  stagnation  will  result.  The  d<;bris-charged  ice  will  then  act  as  a  d.un 
and  check  the  flow  of  the  clearer  iee  above.  The  effect  of  such  a  check  in 
the  advances  of  the  stream  will  vary  with  conditions,  particularly  as  there 
is  a  delicate  adjustment  at  the  extremity  of  a  normal  glficier  between  the 
effects  of  temperature  tending  to  melt  the  ice  and  the  advance  of  fresh  ice 
from  above.  Fresh  ice  may  advance  upon  the  debris-charged  portion  and 
become  in  turn  concentrated,  thus  raising  the  dam  ;  or,  in  the  ease  of  a 
growing  glacier,  may  flow  over  the  obstruction  and  continue  to  advance 
until  melting  and  concentration  of  debris  again  causes  stagnation  at  its 
extremity,  when  the  process  would  be  repeated.  If  the  glacier  is  slowly 
wasting  away,  the  dam  would  check  the  advance  of  ice  from  above  and 
cause  it  to  increase  in  thickness  and  to  expand  in  area,  thus  presenting  a 
broader  surface  to  the  atmosphere.  Now,  the  presence  of  surface  de))ri.s 
influences  the  melting  of  a  glacier  in  two  ways.  When  small  in  amount, 
especially  if  dark  in  color,  it  promotes  liquefaction  ;  but  if  abundant,  it 
protects  the  ice  from  the  sun  and  atmosphere  and  retards  waste.  In  the 
case  of  a  slowly  retreating  glacier  that  has  formed  a  d6bris-charged  ice 

1 1.  C.  Russell,  "  The  Effect  of  Debris  on  the  Flow  of  Glaciers,"  Journal  of  Geology, 
vol.  3,  1895,  pp.  823-832, 


CLIMATIC    CIlANtJES. 


159 


dum,  the  melting  of  the  ( leiir,  or  hut  sliglitly  chaipeil  i('e,ftlx)ve  the  olwtruc- 
tion  will  go  on  nmch  more  rapidly  than  at  the  extremity,  where  the  iee  i» 
covered  with  earth  and  Mtones.  The  iee  alH)ve  the  oiwtruetion  migiit  then 
Ik;  melted,  leaving  the  dam  to  .slowly  wiuste  away  and  finally  leave  a  ter- 
minal moraine.  The  retreating  glacier  hy  again  eoneentiating  debris  in  its 
extremity  would  again  halt,  and  the  [iroeess  Ix;  repeated. 

An  explanation  is  thus  suggestetl  of  the  varying  l)ehavior  of  glaeiei"s 
under  the  same  elinuitie  conditions.  Two  glaciers  supplied  in  their  ndv6 
regions  with  equal  quantities  of  snow,  and  alike  in  all  respects  except  in 
the  amount  of  debris  carried,  would  undergo  the  changes  outlined  above  at 
different  rates.  If  their  percentages  of  deln'is  were  the  same  and  other 
conditions  varied,  their  periods  of  halt  and  advance  or  retreat  wndd  again 
vfiry.  So  divei"se  are  the  conditions  controlling  tiie  flow  of  glaciers  that 
in  no  two  instances  would  their  pulsations  l)e  synchronous,  even  under  the 
same  meteorological  environment. 

While  the  greater  clianges  exhibited  by  glaciers  can  only  he  accounted 
for  by  variation  in  the  supply  of  snow  on  their  n6v6s,  or  changes  in  the 
rate  of  melting,  or  both  of  these  causes  combined,  due  to  meteorological 
fluctuations,  it  seems  evident  that  the  minor  advances  and  retreats  of 
their  extremities  may  be  due  in  part  to  the  effects  of  debris  on  the  flow 
and  on  the  melting  of  the  ice  as  outlined  above. 


CHAPTER  IX. 


HOW   AND   WHY   GLACIERS   MOVE. 

A  REVIEW  of  the  various  hypotheses  that  have  been  advanced  to  account 
for  the  movements  characteristic  of  glaciers,  necessitates  an  extension  of 
the  geographical  limits  set  for  this  book,  since  the  critical  investigation 
of  gl{\eial  phenomena  vas  well  advanced  in  Europe  before  the  fact  tliiit 
glaciers  existed  in  North  America,  with  the  exception  of  the  remote 
Greenland  region,  was  known.  It  is  only  in  recent  years  that  the  detailed 
study  of  existing  glaciers  has  been  undertaken  in  this  country.  Although 
Agassiz  adopted  America  as  his  home,  the  investigations  that  placed  him 
in  the  foremost  rank  of  glacia!'sts  were  carried  out  in  Euro^ic.  It  is  to 
the  physicists  and  geologists  of  Europe  that  we  are  indebted  for  nearly  all 
that  has  been  done  respecting  the  philosophy  of  glacial  motion. 


The  Nature  of  Glacial  Flow.  —  Many  observations  have  been  made 
which  show  that  glaciers  have  motion,  and  in  probably  all  instances  exhibit 
a  well-defined  flow  during  some  portion  of  their  history.  Al^^iough  this 
matter  has  claimed  a  large  amount  of  attention,  it  is  important  to  remem- 
ber that  glacial  ice  frequently  does  not  flow,  and  that  probably  some  part 
of  every  glacier  is  stagnant. 

The  fact  that  glaciers  move  was  first  determined  in  a  qualitative  way 
by  noting  the  changes  that  take  place  in  the  moraines  on  their  surfaces. 
Conspicuous  boulders  resting  on  the  ice  were  observed  to  slowly  change 
their  positions  from  year  to  year  vath  reference  to  fixed  points  on  adjacent 
cliffs.  These  crude  observations  lead  to  measurements  of  the  rate  of  flow. 
In  the  case  of  several  glaciers  of  the  alpine  type,  rows  of  stakes  have  been 
placed  in  the  ice  at  right  angles  to  the  direction  of  movement,  and  their 
displacement  observed  by  means  of  surveying  instruments  from  the  adja- 
cent banks.  In  this  manner  changes  in  the  positions  of  the  stakes  have 
been  measured  from  day  to  day,  and  in  some  instances  even  from  hour  to 
hour.  Many  observations  of  this  nature  have  shown  that  in  the  case  of  a 
river-like  glacier,  the  most  convenient  variety  for  study,  the  maximum 
motion  is  in  the  central  part  and  decreases  toward  the  bordei-s.  It  has 
also  been  found  that  the  rate  of  flow  is  greatest  at  the  rurface,  and  decreajes 
toward  thr  bottom.     When  a  glacier  follows  a  sinuous  course,  the  thread 


HOW    AND    WHY    GLACIEUS    MOVE. 


161 


of  maximum  current  is  deflected  to  the  right  and  left  of  a  medial  line,  in 
the  same  manner  that  the  swift  central  current  of  a  winding  river  is  thrown 
first  against  one  bank  and  then  against  the  other ;  but  the  bends  in  the 
sluggish  ice  current  are  less  abrupt  than  in  the  case  of  the  more  flexible 
water  current. 

The  rate  of  flow  of  a  glacier  varies  from  locality  to  locality,  through- 
out its  length,  in  response  to  irregularities  in  the  valley  it  occupies, 
unequal  distribution  of  the  debris  it  carries,  and  other  reasons.  The  rate 
of  flow  also  varies  with  the  seasons,  being  greatest  in  summer  and  least"  in 
winter.  Similar  but  much  less  pronounced  variations  occur  between  day 
and  night.  These  seasonal  and  daily  changes  comcide  with  variations  of 
temperature,  the  rate  of  flow  increasing  with  an  increase  in  the  amount 
of  heat  that  reaches  a  glacier.  It  is  important  to  note,  however,  that 
although  glaciers  are  sluggish  in  cold  weather,  they  continue  to  flow,  in 
many  instances  at  least,  even  in  the  depth  of  winter.  A  flowing  motion 
in  the  ice  of  piedmont  and  continental  glaciers  is  frequently  evideni  Ivom 
the  arrangement  of  debris  on  their  surfaces.  The  same  fact  is  shown,  also, 
by  the  presence  of  lobes  about  their  margins  which  many  times  become 
well-defined  streams.  Although  no  measurements  have  been  made  of  the 
manner  in  which  the  currents  in  great  ice  sheets  move,  there  is  vo  reason 
for  supposing  thfvt  the  causes  producing  them  are  of  a  different  nature 
from  those  which  urge  an  alpine  glacier  tluough  a  narrow  valley.  If  an 
explanation  can  be  found  for  the  flow  of  a  mountain  ice-stream,  it  is  evident 
that  it  should  explain  the  movements  of  other  types  of  glaciers  as  well. 

The  movements  of  a  glacier  are  usually  greatly  modified  by  local  con- 
ditions. In  seeking  for  general  laws  applicable  to  all  glaciers,  it  will  be 
of  assistance  if  we  can  determine  what  would  be  the  behavior  under  normal 
conditions  of  an  ideal  glacier  composed  of  clear  ice,  flowing  down  a  straight, 
even  channel  of  uniform  width  and  with  a  uniform  gradient  both  of  the 
valley  and  of  the  glacier's  surface.  Let  us  assume  also  that  in  cross  sec- 
tion our  ^deal  glacier  has  the  form  of  half  an  ellips3,  the  division  being 
along  the  longer  axis.  From  what  is  known  concerning  the  behavior  of 
glaciers  we  may  deternune  in  what  manner  our  ideal  ice  stream  would  flow. 

All  students  of  glacial  })henomena  will  agree,  I  think,  that  in  the  ideal 
example  before  us  the  thread  of  maximum  current  would  be  at  the  center 
of  tlie  surface,  and  that  the  rate  of  surface  flow  would  decrease  uniformly 
toward  each  bank ;  also,  that  the  rate  of  flow  would  decrease  uniformly  from 
the  center  of  the  half-ellipse  along  any  of  its  radii.  The  ruinor  axis  of 
the  ellipse  would  divide  a  cross  section  of  the  glacier  into  two  equal  and 


162 


GLACIERS  OF  NORTH  AMERICA. 


m 


similar  figures,  and  similar  points  in  each  half  would  have  a  corresponding 
motion  which  would  differ  from  the  motion  of  all  other  paints  in  the  cross 
section. 

Any  theory  of  glacial  motion  that  is  applicable  to  all  glaciers  should 
account  for  the  flow  of  our  ideal  glacier,  and  also  explain  all  changes  in 
its  movements  resulting  from  alterations  in  the  assumed  conditions.  With 
a  true  and  sufficient  explanation  of  glacial  motioii  in  mind,  we  should  be 
able  to  predict  what  modifications  in  the  flow  of  our  ideal  glacier  would 
result :  if,  for  example,  its  chaiinel  was  no  longer  straight ;  if  changes 
should  be  made  in  the  gradient  of  either  its  bottom  or  surface  ;  if  the  sides 
or  bottom  of  its  channel  should  be  made  uneven  ;  if  its  width  should 
vary ;  if  the  temperature  to  which  it  is  exposed  should  change  either  grad- 
ually from  its  source  to  its  extremity,  or  fluctuate  irregularly  ;  if  the  ice 
should  become  unevenly  charged  with  debris  ;  and  in  fact  any  other 
changes  in  environment  to  which  actual  glaciers  are  subject. 

The  student  who  has  in  mind  the  movements  in  our  ideal  glacier,  and 
attempts  to  trace  the  changes  that  would  result  from  such  a  combinauon 
of  conditions  as  exert  an  influence  on  even  the  simplest  existing  alpine 
glacier,  will  no  doubt  be  willing  to  accept  the  conclusion  reached  by  gla- 
cialists  that  in  any  existing  glacier,  no  two  points  in  any  cross  section,  and 
in  fact  no  two  points  in  any  portion  of  the  ice  stream,  move  at  the  same 
rate  for  any  considerable  time.  In  other  words,  adjacent  molecules  —  or 
other  feniall  divisions  into  which  ice  may  be  assumed  'j  be  divided  — 
throughout  a  glacier  are  moving  at  diffeient  rates.^  That  is,  the  flow  of 
glacial  ice,  in  a  general  way,  at  least,  is  analogous  to  the  flow  of  a  liquid, 

1  Observations  by  Messrs.  R.  H.  Koch  and  Fr.  Klocke  (Philosophical  Magazine,  Fifth 
Sei-ies,  vol.  9,  1880,  pp.  274-277)  on  the  movements  of  a  point  in  a  vertical  plane  in  a  glacier 
indicate  that  the  movements  of  such  a  point  are  much  more  complex  than  has  been  generally 
supposed.  In  the  observations  referred  to  it  was  found  that  a  given  point  at  one  time  moved 
toward  the  source  of  the  glacier,  and  at  another  time  toward  its  extremity.  Two  adjacent 
points  were  found  to  move  in  opposite  directions  at  the  same  time.  The  maximum  move- 
ments occurred  in  the  forenoon,  beginning  with  the  irridation  of  the  glacier  by  the  sun. 
These  morning  movements  were  irregular,  but  on  the  whole  tended  down  the  valley  ;  while 
at  night  the  resultant  in  the  direction  of  movement  was  toward  the  mountains. 

So  far  as  I  am  aware,  these  delicate  observations  have  not  been  repeated,  and  conclusions 
based  on  them  may  not  apply  to  glaciers  in  general. 

Messrs.  Koch  and  Klocke  do  not  state  what  precautions  were  ;,aken  to  shield  their 
instrument  from  changes  of  temperature,  and  it  is  possible  that  their  observations  are  in  error 
from  this  cause.  The  difficulty  of  keeping  a  transit  or  other  similar  instrument  in  adjust- 
ment, when  exposed  to  changes  of  temperature,  makes  it  desirable  that  the  observations 
referred  to  should  be  repeated  with  an  instrument  so  arranged,  perhaps  with  a  prism,  that  a 
fixed  point  on  land  can  be  seen  at  the  same  time  that  the  movements  of  a  point  on  a  glacier 
arc  Measured. 


HOW    AND   WHY   GLACIERS    MOVE. 


163 


or  more  nearly  to  the  flow  of  a  viscous  fluid.  It  must  be  remembered  that 
in  the  above  attempts  to  describe  the  flow  of  an  ideal  glacier,  and  to  sug- 
gest the  nature  of  the  changes  that  would  result  from  modifications  in  the 
conditions  to  which  it  is  subjected,  the  aim  has  been  to  obtalu  a  graphic 
idea  of  how  a  glacier  flows,  without  attempting  to  explain  why  it  flows.  In 
order  to  learn  if  possible  the  nature  and  mode  of  action  of  the  natural 
forces  which  cause  ice  to  move,  and  at  the  same  time  become  more  familiar 
with  glacial  phenomena  in  general,  let  us  review  briefly  some  of  the 
principal  explanations  that  have  been  offered  of  glacial  motion. 

Hypotheses  of  Glacial  Motion.^ 

Several  hypotheses  in  explanation  of  the  characteristic  movements  of 
glaciers  have  been  advanced,  but  no  one  of  them  has  thus  far  met  with 
[;;eneral  acceptance.  H  is  manifestly  the  duty  of  the  geologist  and  geog- 
rapher, however,  to  examine  these  proposed  ex[)lanations,  and  ascertain  so 
far  as  is  possible  how  much  of  each  can  be  safely  accepted,  even  if  it  does 
not  afford  a  sufficient  reason  for  all  of  the  movements  known  to  occur  in 
large  ice  masses.  By  so  doing  we  may,  perhaps,  clertr  the  way  for  renewed 
study,  or  possibly  be  able  to  frame  an  eclectic  theory  from  portions  of 
previous  explanations  which  will  be  satisfactory. 


The  Slidingr  Hypothesis.  —  As  far  back  as  1760,  a?"  stated  by  Tyndall, 
Altman  and  Griiner  proposed  the  view  that  glaciers  move  by  sliding  over 
their  beds.  Nearly  forty  years  subsequently  this  notion  was  revived  by 
De  Saussure,  and  has  therefore  frequently  been  called  "  De  Saussure's 
theory,"  but  is  more  frequently,  perhaps,  designated  as  the  "sliding 
theory"  of  glacial  motion.  Subsequently  the  hypothesis  was  ably  discussed 
by  W.  Hopkins.''' 

Under  this  hyi>othe8is  glaciers  are  supposed  to  slide  bodily  down  the 
valleys  they  occupy,  in  obedience  to  gravity,  and  grind  away  the  rocks 
over  which  they  pass,  by  means  of  sand  and  stones  frozen  into  their  under 
surfaces. 

*  Many  reviews  of  glacial  hypotheses  have  been  published  ;  among  those  that  the  student 
will  find  most  interesting  and  instructive  are  :  "  Thr^  Physical  Cause  of  the  Motion  of  Glaciers," 
in  "  Climate  and  Time,"  by  James  CroU,  llrst  edition,  chapters  30,  31  ;  "  The  Great  Ice  Age,' 
by  James  Geikie,  second  edition,  chapters  3,  4  ;  "  Illustrations  of  the  Earth's  Surface  — 
Glaciers,"  by  N.  S.  Shaler  and  W.  M.  Davis,  chapter  12.  The  last-named  book  also  contains 
a  useful  list  of  works  on  glaciers,  published  previous  to  1881. 

2  "On  the  Motions  of  Glacier,"  Philosophical  Magazine,  vol.  24,  1895,  pp.  607-600 : 
Also,  "On  the  Theory  of  the  Motion  of  Glaciers,"  ibid.,  vol.  25,  1863,  p.  224. 


164 


GLACIEUS    OF    NORTH    AMEUICA. 


It  is  unnecessary  to  discuss  the  sliding  hypothesis,  since,  as  is  now 
unanimously  conceded,  the  normal  movements  to  l>e  observed  in  glacial 
ice  are  of  the  mitt'.re  of  an  onward  flow,  accomplished  by  the  mutual  dis- 
placement of  molecules  of  ice.  It  is  of  interest  to  note,  however,  that 
this  early  and  now  totally  rejected  hypothesis  dov^s  contain  an  element 
of  truth. 

Wlien  glaciers  descend  steep  slopes  they  become  broken,  and  even 
large  r^asses  sometimes  move  short  distances  by  sliding  bodily  downward. 
This,  it  will  be  understood,  is  an  exception  to  the  normf'.  moveniMits 
characteristic  of  glaciers,  and  is  referred  to  simply  to  show  that  even  the 
crudest  of  the  hypotheses  we  are  considering  contains  a  grain  of  truth. 


The  Hypothesis  of  Dilatation.  —  As  the  movements  of  glaciers 
became  better  known,  the  sliding  hypothesis  just  referred  to  wa'-  sup- 
planted by  the  "  hypothesis  of  dilatation,"  advocated  especially  by  Cliar- 
pentier  and  Agassiz.  The  basis  of  this  proposed  explanntion  is  that  water 
on  freezing  expands  and,  if  confined,  will  exert  a  pressure  on  the  walls 
retaining  it.  As  water  penetrates  freely  into  a  glacier  through  fissures 
and  capillary  passages,  it  was  concluded  that  it  would  freeze  in  such  situ- 
ations, and  thus  exert  a  pressure  on  the  ice  containing  it,  and  that  a 
movement  of  the  ice  would  thus  originate  which  would  take  the  direction 
of  least  resistance  ;  and,  as  alpine  glaciers  were  alone  considered,  it  was 
concluded  that  the  direction  of  least  resistance  would  be  down  the  valleys 
they  occupy. 

Tliis  hypothesis,  like  the  one  it  displaced,  met  with  opposition  and  lead 
to  much  discussion.  Better  still,  it  awakened  fresh  interest  in  glacial 
studies  and  led  to  renewed  observations  of  glacial  phenomena. 

Among  the  able  opponents  of  the  dilatation  hypothesis  Avas  W.  Hop- 
kins, who  showed,  by  means  of  mathematical  demonstrations,  that  the 
direction  of  least  resistance  to  expansion  at  most  points  within  a  glacier 
would  be  vertically  upward,  and  that  the  assumed  cause  of  glacial  flow,  if 
really  in  action,  would  cause  a  glacier  to  increase  in  thickness  rather  than 
advance  down  a  valley. 

Many  other  objections  to  the  hypothesis  under  review  have  been 
advanced  from  time  to  time.  It  has  been  shown,  for  example,  that  the 
changes  of  temperature  to  which  glaciers  are  ordinarily  subjected  do  not 
penetrate  far  beneath  the  surface  ;  and  besides,  if  glacial  flow  is  due 
jolely  to  the  freezing  of  water  within  the  ice,  it  should  be  greater  by 
night  than  by  day,  and  greater  in  winter  than  in  summer,  which,  as 


mm 


HOW    AND   WHY   GLAUIEUS   MOVE. 


165 


we  know,  is  the  reverse  of  the  truth.  These  and  other  objections  to 
the  hypothesis  of  dilatation  have  led  to  the  conclusion  that  it  is  in- 
adequate as  a  complete  explanation  of  the  normal  movements  of  even 
alpine  glaciei-s. 

In  closing  this  brief  review  of  a  long  and  instructive  discussion,  I  wish 
to  remind  the  reader  that,  although  the  hypothesis  of  dilatation  as  a  Vv^hole 
has  been  abandoned,  the  labors  of  its  advocates  were  not  in  vain.  It  not 
only  served  a  useful  purpose  in  stimulating  inquiry,  but  that  it  is  based 
on  a  true  principle  must  be  conceded  even  at  this  time  when  several 
younger  and  more  promising  hypotheses  are  in  the  field.  It  cannot  be 
truthfully  denied  that  water  does  freeze  in  cavities  and  capillary  passages 
in  glaciere,  and  in  so  doing  does  exert  a  force  which  tends  to  move  tliem. 
What  the  opponents  of  the  hypothesis  have  demonstrated  is  that  the  force 
appealed  to  is  inadequate  to  brinj^  a"  +he  results  observed,  and  that  it 
is  not  the  only  force  that  tends  to  produce  glacial  motion. 


if''' 
I 


The  Hypothesis  of  Plasticity.  —  The  attempt  to  explain  the  flow  of 
glaciers,  to  which  this  name  has  been  applied,  is  based  essentially  on  two 
principles:  1.  Th.at  ice  is  plastic,  and  will  change  its  form  under  pressure. 
2.  That  ice  in  sufficiently  large  masses,  when  unconfined,  will  flow  under 
the  influence  of  its  own  might.  Each  of  these  propositions  has  been  vig- 
orously assailed,  and  evei,  at  the  present  day  their  correctness  is  not 
admitted  by  eminent  physicists.  More  will  be  said  in  this  connection  in 
advance. 

It  is  stated  by  TyndalP  that  the  first  suggestion  in  reference  to 
glacial  ice  behaving  as  a  plastic  body  was  made  by  Bordier,  in  1773. 
Thi^  germ,  however,  did  not  bear  fruit. 

In  ]  841  Rendu  presented  a  "  Theorie  des  Glaciei's  de  la  Savoie " 
before  the  Royal  Academy  of  Savoy,  in  which  the  idea  that  glacial  ice 
behaves  as  a  plastic  solid  is  clearly  enunciated.  This  important  discussion 
not  only  of  the  movements  of  glaciers,  but  of  many  other  phenomena  con- 
nected with  them,  has  been  republished,  together  with  a  translation  in 
English,  and  may  be  found  in  most  scientific  libraries.'^ 

The  hypothesis  that  glaciers  owe  their  movements  to  the  inherent 
plasticity  of  the  ice  composing  them  found  its  chief  advocate  in  J.  D. 
Forbes,  who  first  applied  the  term  viscous  to  glacial  ice,  and  by  long  con- 
tinued study  and   careful   experiments   sought  to  establish  a  "viscous 

J  "  Forms  of  Water,"  1875,  p.  163. 

a  "Theory  of  the  Glaciers  of  Savoy,"  Macmillan  &  Co.,  1874. 


166 


GLACIERS   OF   NORTH   AMERICA. 


theory"  of  g)acial  motion.  The  formal  h;  pothesis,  as  stated  by  Forbes,^ 
is  :  "A  glacier  is  an  imperfect  fluid  or  visciuis  body,  which  is  urged  down 
a  slope  of  certain  inclination  by  the  mutual  pressure  of  its  parts."  As  the 
terms  viscosity  and  plasticity  are  now  strictly  defined,  although  applied  to 
phenomena  which  in  reality  i.ierge  together,  it  is  advisable  to  change  the 
wording  of  the  hypothesis  under  review,  as  first  stated,  without,  ho.^ever, 
altering  the  meaning  that  was  intended  to  be  conveyed.  We  shall  speak 
of  solids  that  yield  continuous  under  pressure  as  a  plastic  solid,  and  a  fluid 
which  Hows  sluggishly  as  a  viscous  fluid. 

Tlie  conclusion  that  an  alpine  glacier  flows  more  rapidly  in  its  central 
part  than  at  the  sides  was  fii-st  definitely  established  by  Agassiz,  and  after- 
ward verified  by  Forbes.  The  flow  of  a  glacier  was  thus  shown  to  be 
strikingly  analogous  to  the  flow  of  a  river.  This  fact  has  been  so  well 
established,  and  may  be  so  eaeily  verified,  that  we  are  justified  in  saying 
that  a  glacier  flows  in  the  same  manne"  as  a  fluid  body,  that  is,  it  advances 
owing  to  differential  molecular  motion  in  essentially  all  its  parts.  Whether 
the  flow  of  glacial  ice  is  due  to  its  plasticity  under  the  influence  of  its  own 
weight,  or  is  owing  either  wholly  or  in  part  to  other  causos,  I  trust  will 
appear  as  we  advance. 

The  propositions  on  which  the  hypothesis  of  plasticity  are  based  must 
necessarily  be  verified  before  they  can  be  applied  in  explanation  of  the 
behavior  of  glaciers.  Let  us  see  first  of  all  whether  conclusions  have  been 
reached  in  reference  to  the  plasticity  of  ice. 

Ice,  as  we  ordinarily  see  it,  is  a  hard,  brittle  substance,  which  may  be 
shattered  into  angular  fragments  by  a  sharp  blow.  At  the  first  glance  it 
would  seem  that  scarcely  any  statement  could  be  farther  from  the  truth 
than  to  say  that  such  a  substance  is  plastic,  that  is,  will  yield  continuously 
to  pressure  without  fracture.  Manj'  substances,  however,  like  pitch, 
asphaltum,  etc.,  which  at  ordinary  atmospheric  temperatures  are  as  brittle 
as  ice,  and  like  it  may  be  broken  into  angular  fragments  by  a  force  sud- 
denly applied,  Avill,  if  time  be  allowed,  slowly  change  their  form,  or  flow, 
under  the  influence  of  their  own  weight.  Many  experiments  have  been 
made  which  demonstrate  that  ice  under  sufficient  pressure,  if  slowly 
applied,  will  also  change  its  shape  without  being  broken.  Without  digress- 
ing too  far  from  the  main  subject  in  hand,  I  may  state  that  perhaps  the 


1 "  Travels  through  the  Alps  of  Savoy  and  Other  Parts  of  the  Tennine  Chain,  with 
Observations  on  the  Phenomena  of  Glaciers,"  Edinburgh,  1846,  second  edition,  p.  3(5o. 
"Norway  and  its  Glaciers,"  Edinburg'i,  1863.  "Occasional  Papers  on  the  Theory  of 
Glaciers,"  Edinburgh,  1859. 


HOW    AND   WHY   GLACIERS    MOVE. 


167 


most  conclusive  experiments  in  this  direction  have  been  made  by  J.  C. 
McConnel  and  D.  A.  Kidd,^  who  demonstrated  that  a  bar  of  ghicier  or 
other  ice,  if  composed  of  many  crystals,  will  yield  continuously  and  with- 
out fracture  to  both  pressure  and  tension.  That  is,  it  apparently  behaved 
as  a  plastic  solid.  The  greatest  freedom  of  motion  occurred  when  the 
ice  experimented  on  was  near  the  melting  point,  and  decreased  with  a 
deciease  of  temperature.  At  — 2°  C.  its  " plasticity  "  was  twice  as  great 
as  at  —10^  C. 

Further  experiments,  by  McConnel,  with  bare  of  ice  cut  from  single 
crystals,  brought  out  most  interesting  results.  It  was  found  that  when 
such  a  bar  with  the  optic  axis  of  the  cryjtal  perpendicular  to  two  of  the 
side  faces  was  subject  to  bending  stress,  it  would  bend  freely  in  the  plane 
of  the  axis  either  at  or  below  the  freezing  point,  but  not  at  all  in  a  plane 
perpendicular  to  it.  In  the  bent  crystal  the  optic  axis  in  any  part  was 
normal  to  the  bent  faces  in  that  part.  The  crystal  behaved  as  if  it  was 
composed  of  an  infinite  number  of  thin  sheets  of  paper,  normal  to  the  optic 
axis,  attached  to  each  other  by  some  viscous  substance  which  allowed  one 
to  slide  over  the  next  with  great  difficulty. 

The  results  of  the  experiments  just  cited  seem  to  show  that  while  ice 
composed  of  many  crystals  yields  to  both  pressure  and  tension  in  a  manner 
that  is  strikingly  similar  to  the  behavior  of  plastic  substances  under  similar 
conditions,  yet  the  manner  in  Avhich  it  yields  is  decidedly  different.  The 
flow  of  liquids  and  of  viscous  substances  is  accounted  for  by  the  movement 
of  adjacent  molecules  past  each  other,  in  any  direction  ;  in  ice,  motion  in 
response  to  pressure  or  tension  takes  place  along  gliding  planes  which 
have  a  definite  relation  to  the  optical  axis  of  the  crystals. 

The  movements  observed  in  ice  under  pressure  is  not,  therefore,  true 
plasticity,  but,  as  pointed  out  by  McConnel,  is  identical  in  nature  with 
the  displacements  along  planes  observed  in  rock  salt,  Iceland  spar,  and 
other  certain  substances  when  subjected  to  pressure.  For  this  peculiar 
"plasticity"  no  definite  name  has  been  proposed.^ 

1  "On  the  Plasticity  of  Glaciers  and  Other  Ice,"  Proc.  Roy.  Soc,  London,  vol.  44,  1888, 
pp.  331-307.  Also,  J.  C.  McConnel,  "On  the  Plasticity  of  an  Ice  Crystal,"  Ibid.,  vol.  48, 
1890,  pp.  256-260  ;  vol.  49,  1891,  pp.  823-343. 

2  The  experimenta  by  McConnel  and  Kidd  cited  above  have  recently  been  repeated  by 
Dr.  O.  Miigge,  and  are  described  by  Cl'aniberliu,  iu  the  Journal  of  Geology,  vol.  3,  181»&, 
pp.  905,  060,  as  follows  : 

"  Prisms  were  cut  from  carefully  formed  ice  in  various  directions  to  the  principal  crys- 
tallographic  axis,  i.e.  the  optic  axis  of  the  crystal,  particularly  in  directions  parallel  and 
transverse  to  it.  These  were  tested  by  placing  their  ends  on  supports,  and  weighting  them  in 
the  center.    In  testing  the  transverse  prisms,  the  optic  axis  was  firt^t  placed  in  a  vertical  posi- 


168 


GLACIERS   OP   NORTH   AMERICA. 


Experiments  by  Tyiidall  on  the  moulding  of  ice  into  various  shapes, 
by  pressure  applied  with  comparative  rapidity,  will  be  referred  to  in 
advance  in  connection  with  the  consideration  of  another  property  of  ice, 
namely,  revelation. 

The  manner  in  which  glaciiu  ice  moulds  itself  to  the  inequalities  of 
the  rocks  over  which  it  flows,  so  as,  in  many  instances,  to  polish  and  striate 
the  bottoms  and  sides  of  narrow  trenches,  and  even  the  under  surfaces  of 
projecting  ledges,  is  undeniable  evidence  that  it  behaves  as  a  plastic  body. 
One  of  the  objections  urged  against  the  idea  that  ice  is  plastic  is  that 
although  it  yields  to  pressure,  it  is  supposed  not  to  yield  to  tension,  and 
hence  lacks  one  of  the  properties  of  a  ulastic  substance.  The  formation 
of  cracks  in  glaciei's  is  frequently  cited  as  proof  that  ice  breaks  under  t(;n- 
sion.  This  conclusion  was  held  by  Tyndall,  who  apparently  demonstrated 
by  delicate  experiments  that  ice  would  not  yield  to  tension  except  by  frac- 
ture. More  recent  experiments  by  McConnel  and  Kidd,  already  cited, 
have  shown,  however,  that  ice  does  stretch  under  tension  when  slowly 
applieu.    The  widening  of  crevasses,  frequently  to  be  observed  both  in  neve 

tion.  The  prisms  sagged,  and  their  ends  were  drawn  inward.  Optical  examination  showed 
that  tlie  optic  axis  remained  normal  to  the  bent  surface.  Subsequent  observations  on  surfaces 
fractured  for  tlie  purpose  showed  striation  and  other  indications  that  plates  of  the  crystal 
parallel  to  the  basal  plane  had  sheared  upon  one  another. 

"  When  similar  prisms  were  placed  so  i,hat  these  gliding  planes  stood  on  edge,  no 
appreciable  results  followed,  even  though  greater  weights  and  longer  timos  were  employed. 

"  When  prisms  cut  parallel  to  the  principal  axis  were  tested,  the  gliding  planes  being 
transverse  to  the  prism,  the  weight  sunk  sharply  into  the  upper  face  of  the  prism  and  a  corre- 
sponding protrusion  apjieared  below.  As  the  process  continued,  the  protrusion  below  kept 
closely  parallel  to  the  indentation  above,  both  widening  somewhat  until  a  section  of  the  prism 
had  been  pushed  entirely  out.  Optical  examination  showed  that  the  optic  axis  remained  par- 
allel to  itself  throughout.  The  block  remained  transparent  and  free  from  fracture.  The 
weight  appeared  to  have  simply  slipped  the  plates  over  their  neighbors,  carrying  the  adjacent 
ones  forward  with  them  to  some  extent  by  dragging,  but  not  visibly  affecting  the  more 
remote  ones. 

"  If  the  prism  be  made  of  square  cards  and  placed  on  its  side,  and  a  transverse  force 
applied,  the  result  will  illustrate  the  apparent  metliod  of  movement  within  the  ice  crystal  in 
this  last  case.  If  such  a  prism  be  pressed  at  right  angles  to  the  cards,  it  will  illustrate  the 
bending  of  the  first  case,  and  if  the  cards  be  placed  on  edge,  they  will  illustrate  the  effectual 
resistance  to  deformation  of  the  first  case.  Variations  of  temperature  through  10°  were  not 
found  to  produce  notable  differences  of  result. 

"  Not  to  mention  other  significant  points,  the  investigation  seems  to  warrant  the  impor- 
tant conclusion  that  ice  crystals  yield  to  deforming  forces  by  the  sliding  or  shearing  of  the 
crystalline  layers  at  right  angles  to  the  principal  axis.  No  analogy  to  the  motion  of  a  viscous 
fluid  appeared.  Dr.  MUgge  had  previously  found  a  similar  method  of  deformation  in  other 
minerals,  including  gypsum,  stilbite,  and  vivianite.  In  respect  to  its  mode  of  internal  motion, 
ice  is  therefore  to  be  classed  with  these  minerals,  rather  than  bodies  properly  called 
viscous." 


HOW  AND  WHY  GLACIERS  MOVE. 


169 


regions  and  in  the  ice  of  the  lower  portions  of  glaciers,  also  snstains  the 
same  conclusion  As  in  the  case  of  the  compression  of  ice,  its  ability  to 
stretch  under  tension  is  lowered  by  a  decrease  of  temperature. 

Without  attempting  to  review  at  this  time  all  that  has  l)een  written 
concerning  the  plasticity  of  ice,  it  seems  safe  to  conclude,  on  the  strength 
of  the  experiments  and  observations  just  cited,  as  well  as  many  others 
which  might  be  given,  that  ice  under  pressure  slowly  applied  can  ')e  made 
to  flow.  That  ice  is  truly  plastic^  however,  is  not  sustained  by  the  ex})eri- 
ments.  The  question  how  much  pressure  would  be  required  to  i)roduce 
the  flow  observed  in  glaciers  still  remains.  This  is  a  more  diflicult 
question,  and  perhaps  does  not  admit  of  precise  determination. 

The  conclusion  reached  by  Forbes  and  others,  that  glaciers  flow  by 
reason  of  their  own  weight,  that  is,  ice  is  sufficiently  plastic  to  shear  under 
the  influence  of  gravity,  has,  in  the  opinion  of  many  physicists,  been 
demonstrated  by  the  bending  of  planks  of  ice  when  supported  at  their 
extremities.  That  planks  of  ice  will  bend  under  such  conditions  has  . 
been  shown  by  experiments,  and  also  by  observing  the  behavior  of  blocks 
of  ice  in  Arctic  regions,  which  slowly  sag  when  supported  at  opposite 
edges,  even  when  the  temperature  is  continuously  far  below  freezing.  In 
the  bending  of  a  plank  of  ice  under  its  own  weight,  there  must  of  neces- 
sity be  a  compression  of  the  material  on  the  upper  side  and  an  extension 
on  the  lower  side.  In  other  words,  the  behavior  of  ice  under  the  influence 
of  gravity  is  similar  to  that  of  plastic  bodies  under  like  conditions.  ^ 

Certain  experiments  cited  by  Henry  Moseley,  ho^^ever,  have  been 
claimed  to  show  that  the  weight  of  an  ice  mass  is  insufficient  to  cause  it 
to  change  its  shape,  or  shear,  in  the  manner  in  which  many  plastic  solids 
are  known  to  do  under  the  influence  of  their  own  weight.  But  in  the 
experiments,  referred  to  the  difference  in  the  behavior  of  ice  under  pres- 
sure when  slowly  applied  and  when  applied  with  comparative  rapidity  is, 
in  the  opinion  of  several  competent  judges,  not  sufficiently  recognized. 
As  shown  by  Moseley,  the  force  necessary  to  shear  a  column  of  ice  one 
square  inch  in  area  of  cross  section,  when  applied  in  the  course  of  15 
or  20  minutes,  is  about  75  pounds,  or  34  times  th?  computed  portion  of 
gravity  available  in  producing  glacial  flow,  and,  therefore,  these  glaciers 
cannot  move  by  reason  of  their  own  weight. 

Moseley's  experiments  have  been  repeated  by  other  physicists,  and  also, 
in  part,  by  the  present  writer,  with  essentially  the  same  results,  so  far  as 


1  This  conclusion  is  hold  by  William  Mathews  and  others. 
212,  1871,  pp.  332-534. 


Philosophical  Magazine,  vol. 


'I 


170 


GLACIEUS   OF   KOHTH    AMEUICA. 


the  amount  of  force  required  to  shear  ice  under  the  conditions  olwerved 
in  the  experinuM :  us  are  concerned.  That  the  conclusions  readied  from 
these  exi)erinients  can  be  applied  in  explaining  glacier  motion  cannot  he 
so  readily  accepted. 

The  experiments  made  by  Moseley  have  been  discussed  by  J.  Ball ' 
and  others,  who  have  shown  that  the  time  element  is  important,  and  that 
there  are  reasons  for  doubting  if  the  results  reached  can  be  applied  in 
explanation  of  the  flow  of  glaciers. 

Although  the  conclusion  that  ice  will  flow  under  the  influence  of  its 
own  weight  may  not  be  established  to  the  satisfaction  of  all  who  are  inter- 
ested in  the  problem,  yet  if  applied  provisionally  t  >  glaciers  it  is  found  to 
explain  many  of  their  movements,  and  enables  one  to  predict  what  will 
occur  under  given  conditions. 

By  comparing  the  movements  of  glaciers  with  the  movements  of  pitch 
and  other  similar  bodies  vmder  the  influence  of  gravity,  striking  analogies 
may  be  obtained.  If  pitch  of  the  proper  cons'stency  be  placed  in  a  gently 
inclined  trough,  haviug  so  far  as  practicable  the  proportions  of  a  repiesen- 
tative  glacier-filled  valley,  it  will  slowly  descend  in  the  same  manner  that 
glaciers  move,  even  though  it  is  extremely  brittle  at  the  temperature  at 
which  the  experiment  is  conducted.  The  flow  of  the  pitch  is  most  rapid 
in  the  central  part  of  the  surface  of  the  stream,  but  decreases  gradually  in 
rate  of  flow  towards  the  sides  and  bottom.  If  two  streams  of  pitch  be 
made  to  unite  so  as  to  form  a  trunk  stream,  representing  a  compound  glr.- 
cier,  lines  of  debris  on  the  borders  of  the  tributaries,  representing  lateral 
moraines,  will  units  and  forma  "medial  moraine."  Where  inequalities 
in  the  bottom  of  the  trough  exist,  crevasses  will  appear  in  the  pitch,  etc. 
In  this  and  other  ways  the  flow  of  a  glacier  may  be  shown  to  correspond 
in  a  most  striking  manner  with  the  flow  of  a  plastic  substance  which  is 
urged  forward  solely  by  the  influence  of  its  own  weight.  Strong  as  are 
the  argumei.^s  tending  to  show  that  glaciers  are  urged  forward  in  the  same 
manner  that  truly  plastic  suljstances  flow  under  the  influence  of  gravity, 
this  explanation  has  not  been  unanimously  accepted. 

Many  forcible  objections  to  the  hypothesis  of  plasticity  have  recently 
been  advanced  by  T.  C.  Chamberlin."  These  objections,  however,  are 
based  principally  on  observations  ma^e  on  the  glaciera  of  Greenland,  where 
the  generally  low  temperature  may  be  considered  as  reducing  the  plasticity 

^"On  the  Cause  of  the  Motion  of  Glaciers,"  Philosophical  Magazine,  vol.  42,  1871, 
pp.  81-87. 

2  "  Recent  Glacial  Studies  in  Greenland,"  Bull.  Geol.  Soc.  Am.,  vol.  6,  1894,  pp.  199-220. 


now    AND    WHY   OLAC»EH8    MOVE. 


171 


of  ice  to  its  lowest  limit  us  exliihited  in  glivcioi*s.  Whether  this  condition, 
however,  may  render  the  observations  Ijss  valuahle  for  determining  tlie 
existence  of  phisticity,  or  make  the  test  more  searcliing,  might  be  dift'erently 
conclnded. 

Chaniberlin  states  that  his  ohservations  seem  to  Ije  adverse  to  anytliing 
wliicli  can  be  termed  viscous  fluency.  In  some  instances  the  surfaces  of 
glaciei"S  were  found  to  rise  in  the  direction  of  tlic  motion  of  the  ice,  so 
that  surface  streams  flowed  backward.  Similar  changes  in  surface  slope 
were  observed  by  the  i)resent  writer  in  several  instances  in  tiie  neves  of 
Alaska,  and  is  evidently  not  exceptional.  This  phenomenon  may,  how- 
ever, not  bo  opposed  to  the  hypothesis  of  plasticity,  since  the  energy  wliich 
urges  forward  a  given  molecule  within  a  glacier  is  the  resultant  pressure 
of  molecules  at  higher  levels.  It  is  principally  the  surface  gradient  that 
determines  the  rate  of  flow.  The  formation  of  elevations  analogous  to 
anticlinal  folds  may  be  due  to  the  pressure  of  ice  at  higher  elevations, 
acting  as  a  thrust  on  the  edges  of  layers,  the  cohesion  of  which  is  suthcient 
to  allow  them  to  bend  upward  and  revei-se  the  nonnal  surface  gradient. 

The  breaking  of  glacial  ice  under  moderate  and  slowly  acting  tension 

• 

was  also  observed  by  Chamberlin,  who  concludes,  as  others  have  done, 
that  if  the  ice  could  stretch  even  in  a  slight  degree,  crevasses  would  in  many 
instances  be  avoided  in  situations  where  they  are  found  in  abundance. 
As  the  ability  of  ice  *o  stretch  decreases  with  temperature,  it  is  to  be  ex- 
l)ected  that  in  the  far  north  the  conditions  are  unfavorable  for  the  stu^^y 
of  such  phenomena.  On  the  whole,  the  observations  thus  far  made  on  the 
breaking  of  glacial  ice  and  the  formation  of  crevasses,  do  not  seem  to 
controvert  the  results  of  experiments  which  show  that  ice  does  yield  to 
slowly  applied  tension,  without  rupture.  What  has  been  shown  by  gla- 
cialists  in  many  countries,  is  that  the  limit  to  which  glacial  ice  can  yield 
to  tension  under  certain  conditions  is  frequently  exceeded.  It  was  also 
noticed  that  boulders  resting  on  the  glaciers  in  Greenland,  or  inclosed 
within  them,  showed  no  tendency  to  descend  through  the  ice  a«  heavy 
substances  descend  through  viscous  bodies.  This,  as  is  well  known,  is 
true  of  bouldei-s  carried  by  glaciera  in  all  countries,  and  offei-s  an  objection 
to  the  hypothesis  of  plasticity  that  cannot  be  easily  removed. 

Everywhere,  as  stated  by  Chamberlin,  the  ice  of  the  Greenland  glaciers 
appeared  to  behave  as  a  rigid  rather  than  as  a  plastic  substance.  The 
rigidity  did  not  prevent  contortions  and  foldiivgs  of  the  laminated  ice,  but 
faults  and  vein  structure  also  occurred,  and  there  seemed  to  be  no  more 
occasion  to  assume  plasticity  in  the  one  case  than  in  the  other. 


172 


GLAClKUy   or    NOUTH    AMERICA. 


Tlie  Haine  autyio"  also  remarkn  "  that  there  w  a  theoretical  objection  to 
the  aH8umj)tiou  of  vihcoum  Hovvage  in  the  very  fact  of  crystallization  itself. 
The  property  of  viscous  tlovvafjfe  rests  upon  the  relative  imlifference  of  u 
particle  as  to  its  special  point  of  adhesion  to  its  neighbor  particles.  Tin; 
pr()|)crty  of  crystallization  rests  upon  the  strongest  preferences  respecting,' 
such  relationshi[)s.  Particles  of  w/ater  in  their  fluid  condition  lie  against 
and  cohere  to  each  other  indiffei'^ntly.  When  they  take  on  a  crystalliru- 
form  they  arrange  themselves  in  specific  relationships  by  the  exercise  of  a 
force  of  the  highest  order.  In  the  presence  of  this  very  forceful  disposi- 
tion of  the  particles  to  retain  fixed  relationships  to  each  other,  it  would 
seem  little  less  than  a  contradiction  of  terms  to  attribute  to  them  viscous 
tlowage.  The  crystalline  body  may  readily  Ix)  made  to  change  it«  form  l)y 
the  removal  of  particles  from  one  portion  by  melting  and  their  attachment 
at  other  points  by  congelation,  but  not,  I  think,  by  the  flowing  of  crys- 
tallized particles  over  each  other  while  in  their  crystallized  condition." 

While  some  of  the  objections  to  the  hypothesis  of  plasticity  advanced 
by  Chamberlin  are  at  present  unanswerable,  and  his  general  conclusion  in 
reference  to  the  rigidity  of  the  ice  at  the  north  of  much  weight,  yet  the 
theoretical  considerations  just  quoted  would  seem  to  be  more  than  counter- 
balanced by  the  experiments  which  show  that  ice  composed  of  many 
crystals  does  yield  continuously  without  fracture  both  to  compression  and 
tension.  If  a  slab  of  ice  supported  at  its  ends  does  gradually  sag  under 
the  influence  of  its  own  weight,  simply,  and  at  temperatures  that  do  not 
admit  of  melting  and  refreezing,  it  seems  unnecessary  to  argue  that  on 
account  of  its  crystalline  structure  it  is  impossible  for  it  so  to  yield. 

The  discussion  that  has  been  carried  on  for  half  a  century  respecting 
the  hypothesis  of  plasticity  has  been  ably  advocated  on  each  side,  and 
some  of  the  arguments  against  it  remain  unanswered  ;  but  to-day  many  able 
investigators,  and  especially  many  of  those  who  are  familiar  with  glaciers 
from  actual  contact  with  them,  I*;  d  that  it  more  nearly  meets  the  re- 
quired conditions  than  any  other  'hypothesis  that  has  been  proposed.  That 
it  is  not  a  complete  and  sufficient  explanation  of  all  the  phenomena  asso- 
ciated with  the"  flow  of  gla  jers,  however,  will  appear  still  more  forcibly, 
I  think,  from  a  review  of  other  explanations  that  have  been  proposed. 


The  Hypothesis  of  Regelation.  It  is  now  well  known,  thanks  tf) 
Faraday,  Tyndall,  and  others,  that  when  two  pieces  of  ice  having  a  tem- 
perature of  about  32°  F.  are  brought  in  contact  they  freeze  together. 
This  property,  now  termed  regelation,  was  studied  especially  by  Tyndall, 


HOW    AND    WHV    OLACIEKS    MOVE. 


178 


and  by  him  first  UHed  in  attempting  to  explain  plaoier  motion.  Under  the 
hy[)Othe.si.s  of  ivgehition  the  ice  of  ghu-ieix  is  thought  to  l)e  crushed  and 
tiio  fragments  reunited  hy  refreezing  after  a  change  of  position.  "It  is 
easy,  therefore,"  says  TyiuhiU,  "  to  understand  how  a  substance  so  endowed 
can  l)e  scjueezed  through  the  gorges  of  the  AIjjs,  can  bend  so  as  to  accom- 
modate itself  to  the  flexures  of  the  Alpine  valleys,  and  can  permit  a  dif- 
ferential motion  of  its  partw  without  at  the  same  time  possessing  a  single 
trace  of  viscosity." 

In  illustration  of  the  process  of  regelation  numerous  experiments  have 
been  made  by  placing  fragments  of  ice  in  moulds  of  various  forms,  and 
subjecting  them  to  pressure.  When  thus  treated  the  ice  is  crushed  and 
the  fragments  move  past  each  other  so  as  to  take  new  positions,  and  are 
thus  adjusted  to  the  shape  of  the  cavity  containing  them,  but  freeze  to- 
gether in  their  new  positions  and  form  a  solid  body.  In  this  manner  ice 
has  been  made  to  assume  almost  any  desired  t'hape.  When  the  pressure 
is  slowly  applied  loide  fracture  is  avoided  and  the  ice  changes  its  shape  in 
apparently  the  same  manner  as  many  plastic  substances  would  if  experi- 
mented with  in  a  similar  way. 

In  applying  the  principle  of  regelation  to  account  for  the  flow  of 
glaciere,  it  is  assumed  that  the  ice  is  crushed  and  that  the  fragments  are 
made  to  move  past  each  other  and  are  refrozen  in  new  positions.  That 
rude  fractures  may  l)e  healed  by  regelation  is  abundantly  attested.  When 
a  glacier  passes  down  a  steep  descent  it  is  greatly  crevassed,  but  below 
such  an  ice  fall  the  fissures  frequently  close,  their  walls  freeze  together, 
and  the  ice  is  possibly  even  more  compact  and  homogeneous  than  before  it 
was  fractured.  The  conclusion,  however,  that  the  characteristic  flow  of 
glacial  ice  is  accomplished  in  the  same  manner,  but  by  incipient  fractures, 
has  been  seriously  questioned. 

In  the  hypothesis  of  regelation,  as  in  the  hypothesis  of  plasticity,  the 
force  which  causes  motion  is  assumed  to  be  the  weight  of  the  ice.  Instead 
of  flowing  as  a  plastic  substance,  however,  the  ice  is  considered  as  behav- 
ing as  a  brittle  substance,  under  the  conditions  to  which  it  is  subjected, 
and  as  being  crushed  and  having  the  fragments  reunited  by  freezing  after 
a  change  in  their  relative  positions.  In  all  of  the  experiments  that  have 
been  made  to  illustrate  the  process  of  regelation  a  force  greater  than  the 
weight  of  the  ice  experimented  on  has  been  applied.  Much  discussion  has 
been  carried  on  in  reference  to  the  regelation  of  ice  once  fractured  and 
having  its  fragments  brought  in  contact  at  the  proper  temperature  ;  but 
little  has  been  said,  however,  in  reference  to  the  manner  in  which  glaciera 


174 


GLACIERS   OF    NORTH   AMERICA. 


might  be  crushed  so  as  to  make  regelatiop  possible.  As  has  been  shown 
by  Moseley,  a  pressure  of  about  75  pounds  per  square  inch  is  necessary 
to  shear  ice  if  applied  with  comparative  rapidity.  Although  it  seems 
impossible  to  appl}^  these  experiments  in  a  quantitative  way  in  explain- 
ing the  movement  of  glaciers,  they  indicate  that  certain  general  con- 
clusions may  be  valid.  From  the  experiments  referred  to  it  has  been 
computed  that  a  column  of  ice  in  order  to  begin  to  crush  at  its  base 
would  have  to  be  over  700  feet  high.  Evidently,  then,  glacier  ice 
caniiot  be  crushed  under  its  own  weight  unless  at  least  700  feet  thick, 
and  then  the  fracturing  would  be  confined  to  the  bottom  layer  ;  we  shoukl, 
therefore,  under  the  hypothesis  of  regelation,  expect  the  greatest  freedom 
of  move  lent  to  occur  in  the  basal  position  of  a  glacier.  Yet,  as  is  well 
known,  the  maximum  movement  is  at  the  surface.  How,  then,  can  the 
principle  of  regelation  be  applied  in  explaining  the  surface  flow,  especially 
of  a  glacier  with  a  low  surface  gradient  ?  Again,  regelation  takes  place  at 
a  temperature  of  about  32°  F.,  and  cannot  occur  much  below  that  temper- 
ature unle'^s  the  ice  is  und  \t  pressure.  The  rate  at  which  the  melting- 
point  of  ice  Is  lowered  by  pressure  is  so  small  that  practically  it  may  be 
ignored  in  this  discussion.  Besides,  the  rate  of  surface  flow  of  a  glacier  is 
greater  than  the  rate  below  the  surface,  even  in  winter,  when  the  tempera- 
ture of  the  ice  is  frequently  far  below  the  point  where  regelation  is  possible. 
It  seems, '  therefore,  that  the  regelation  hypothesis  fails  to  meet  several 
important  features  of  the  problem  of  glacier  motion. 

The  principle  of  regelation  is  not  to  be  entirely  discarded  in  seeking 
an  explanation  of  the  behavior  of  glaciers,  however,  as  the  healiiig  of 
fractures,  as  already  noticed,  may  be  satisfactorily  explained  in  this 
manner.  The  principle  of  regelation  apparently  assists  one  in  under- 
standing hvHv  the  granular  snow  of  neves  becomes  consolidated  under 
pressure  into  compact  ice.  As  a  neve  becomes  deeper  and  deeper,  the 
granules  of  which  it  is  composed,  but  which  originate  and  increase  in 
size  from  other  jsauses,  are  brought  in  contact  at  the  proper  temperature 
and  freeze  together.  The  granules  formed  from  light,  porous  snow  may 
by  this  process  be  converted  into  compact  ice. 

It  will  undoubtedly  occur  to  the  reader  that  the  question  whether  a 
glacier  flows  by  reason  of  its  plasticity  or  on  account  of  fracture  and  rege 
lation,  could  be  decided  by  a  study  of  the  intimate  structure  of  the  ice  of 
which  it  is  composed.  From  a  geological  point  of  view  glacier  ice  may  l)e 
considered  as  a  "rock'"  and  investigated  by  petrographical  methods.  That 
is,  it  may  be  cut  into  thin  sections  and  examined  by  means  of  the  micro- 


HOW   AND    WHY   GLACIERS   MOVE. 


175 


scope  and  polariscope.  As  already  described,  glacier  ice  b  .3  a  peculiar 
grain,  wbicb  is  frequently  so  pronounced  and  cbaracteristic  tbat  even  a 
small  fragment  may  in  many  instances  be  readily  distinguished  even  by 
the  unaided  eye  from  lake  and  other  ice.  If  the  flow  of  glaciers  is  due 
to  plasticity  one  would  expect  that  the  grain  of  the  ice  would  exhibit 
something  of  a  fibrous  structure,  similar  perhaps  in  a  general  way  to  the 
structure  of  wrought  iron,  or  to  the  structure  of  cerkan  schistose  rocks 
which  have  passed  through  a  plastic  condition.  Nothing  resembling  this 
structure,  however,  is  revealed  in  tlie  grain  of  glacier  ice.  The  struc- 
ture of  a  characteristic  sample  oi  glacier  ice,  when  examined  by  means 
of  a  polariscope,  is  shown  in  the  accompanying  figures,^  one  of  which 


A  B 

Fig.  10.  —  Steucture  of  Glacial  Ice.    (Afteb  Pkeley  and  Fletcher.) 

A  two-thirds  natural  size.    Hie  section  is  vertical  anil  at  righ*.  angles  to  the  tlirection  of  flow, 
B  natural  size.    The  section  is  vertical  and  parallel  with  the  direction  of  flow. 

exhibits  the  appearance  of  a  thin  section  cut  parallel,  and  the  other  at 
right  angles  to  the  direction  of  flow.  Although  the  grains  ir.  the  section 
parallel  with  the  direction  of  flow  are  perhaps  slightly  flattened,  nothing 
resembling  a  fibroutj  structuie  or  a  marked  elongation  of  the  granules  is 
apparent. 

Expeiiments  by  A.  Heim,^  have  shown  that  the  peculiar  grain  of  glacier 
ice  is  accurately  imitated  when  ordinary  lake  ice  is  crushed  and  again  con- 
solidated by  regelation.  So  far  as  the  study  of  the  intimate  structure  of 
glacier  ice  bears  on  the  explanations  of  glacier  motion  already  considered, 

*  These  diagrams  are  copied  from  a  paper  on  "  Tlie  Structure  of  Glacier  Ice  and  its  Bearing 
upon  Glacier  Motion,"  by  11.  M.  Deeley  and  Geoi^  Fletcher,  Geological  Magazine  (London), 
Decade  4,  vol.  2,  1896,  pp.  152-102. 

i' "  On  Glaciers,"  I'hilosophical  Ma,gazine,  vol.  41,  1871,  pp.  485-508.  Translated  from 
Poggendorff's  Annulen,  Erganzunpband,  1870,  pp.  .30-63. 


m 


176 


GLACIERS   OF    NORTH   AMERICA. 


it  favors  the  hypothesis  of  regehxtion  rather  than  that  of  plasticity.  Yet, 
the  observed  uniformity  in  the  size  of  granules  composing  glacier  ice  at 
various  localities  and  their  gradual  increase  in  size  from  near  the  source 
of  a  glacier  but  below  the  lower  limit  of  the  neve  to  its  extremity,  aie  not 
accounted  for  on  the  supposition  that  continual  crushing  and  refreezing 
take  place. 


The  Hypothesis  of  Expansion  and  Contraction.  —  Geologists  are 
familiar  with  the  fact  that  talus  slopes,  a::  the  piles  of  loose  rock  fragments 
at  the  bases  of  steep  escarpments  are  termed,  experience  a  slow  down- 
ward crcep^  due  to  the  alternate  expansion  and  contraction  of  the  frag- 
mentg  composing  them,  with  changes  of  temperature  assisted  by  gravity. 
In  a  similar  way  sheets  of  lead,  as  observed  by  Moseley,  will  slowly  creep 
down  an  inclined  surface  when  exposed  to  variations  of  temperature. 
Glacier  ice  is  exposed  to  changes  of  temperature  and  subject  to  similar 
variations  in  volume,  but  owing  to  the  fact  that  the  same  change  of  tem- 
perature will  produce  greater  changes  in  ice  than  in  rocks  or  lead,  th-^t 
owing  to  its  greater  coefficient  of  expansion,^  its  movements  under  the 
same  fluctuations  of  temperature  will  be  greater. 

It  is  claimed  by  the  advocates  of  the  hypothesis  under  review,  that  in 
the  case  of  an  alpine  glacier,  for  example,  the  ice  in  alternately  contract- 
ing and  expanding  will  slowly  creep  down  a  valley,  since  movement  in 
that  direction  is  assisted  by  gravity  and  in  the  opposite  direction  is  opposed 
to  gravity.  The  same  argument  has  been  applied,  also,  to  continental 
glaciers  originating  on  a  plain  and  flowing  in  all  dii*ections  froin  a 
center  of  accumulation,  since  on  account  of  the  rise  of  the  surface 
gradient  from  the  periphery  toward  the  center  of  the  mass,  the  weight 
of  ice*  acting  on  any  point  in  the  glacier  is  greater  in  one  direction  than 
in  othei-s. 

This  hypothesis  of  alternate  dilation  and  contraction  was  advanced 
by  Moseley^  and  sustained  by  strong  arguments  and  suggestive  experi- 
ments, but  has  been  severely  criticised  by  BalH  and  others.  Among  the 
objections  suggested  in  reference  to  it  are  the  following  : 

1  The  coefficient  of  expansion  of  ice  ia  nearly  twice  that  of  lead,  and  more  than  twice  that 
of  any  other  solid. 

*  "  On  the  Motion  of  a  Plate  of  Metal  on  an  Inclined  Plane,  when  Dilated  and  Contracted  ; 
and  on  the  Descent  of  Glaciers,"  Philosophical  Magazine,  fourth  Series,  vol.  23,  1862,  pp. 
72-79. 

•"  On  the  Cause  of  the  Descent  of  Glaciers,"  Philosophical  Magazine,  Fourth  Series,  vol. 
do,  1870,  pp.  1-10. 


HOW   AND   WHY   GLACIERS    MOVE. 


177 


A  glacier  lying  in  a  high-grade  mountain  valley  or  flowing  from  a 
center  of  accumulation  on  a  plain,  would,  if  it  experienced  changes  of 
temperature,  alternately  contract  and  expand,  and  these  changes  in 
volume  should  produce  a  resultant  motion  in  the  direction  of  least 
resistance.  The  direction  of  least  resistance  at  nearly  all  points  in  a 
glacier  is  upward,  hence  in  general  the  movements  in  a  glacier  result- 
ing from  contraction  and  expansion  would  be  in  a  direction  normal  to 
the  surface  of  the  ice. 

The  changes  of  temperature  which  might  be  expected  to  cause  a 
glacier  to  "  creep  "  are  such  as  affect  it  below  the  melting-point  of  ice,  for 
if  raised  above  that  temperature  it  will  melt.  Observations  have  .ihown 
that  the  internal  temperature  of  glaciers  is  uniformly  32°  F.,  but  extended 
measui-ements  in  this  connection,  especially  in  winter,  are  wanting.  We 
know,  however,  that  so  long  as  the  interstices  of  ice  are  occupied  by  water 
the  temperature  of  the  mass  cannot  vary  sensibly  from  that  just  stated, 
the  effect  of  pressure  being  disregarded  ;  and  as  glaciers,  at  least  in  tem- 
perate latitudes,  are  as  a  rule  saturated  with  v/ater  in  summer,  they  must 
have  a  uniform  temperature  at  that  season  of  32°  F.  In  winter  the  tem- 
perature of  the  air  above  a  glacier  may  fall  far  below  freezing,  and  if  such 
a  change  should  be  continued  long  enough  the  temperature  of  the  entire 
glacier  would  be  correspondingly  lowered. 

With  the  above  considerations  in  mind  it  is  evident  that  under  the 
"  creeping  hypothesis "  the  rate  of  flow  of  a  glacier  should  be  greater 
in  winter  than  in  summer,  and  should  also  be  more  rapid  by  night 
than  by  day.  This  seems  to  be  a  crucial  test  which  reduces  the 
hypothesis  to  an  absurdity,  since  we  know  that  glaciers  flow  more 
rapidly  in  summer  than  in  winter,  and  that  their  motion  is  greater  by 
day  than  by  night. 

If  additional  evidence  of  the  inadequaviy  of  the  hypothesis  of  dilatation 
id  contraction  was  desired,  the  slow  conductivity  of  both  ice  and  snow, 
dad  the  manner  in  which  glaciera  are  invariably  blanketed  with  snow 
throughout  a  large  part  of  the  year  might  be  considered.  For  example, 
in  neve  regions,  the  loose  granular  snow  is  frequently  hundreds  of  feet, 
deep,  and  is  not  only  an  exceedingly  poor  conductor  of  heat,  but,  on  account 
of  its  open  texture,  would  undergo  but  slight  changes  in  mass  on  account 
of  changes  in  temperature,  since  slight  movements  of  the  granules  would 
be  taken  up  by  the  adjacent  interspaces.  It  does  not  require  accurate 
observations  to  show  that  in  such  regions  changes  of  temperature  are  too 
brief  to  be  felt  at  any  considerable  depth,  and  even  under  the  most  ex- 


178 


GLACIERS   OF   NOllTH    AMEUICA. 


treme  conditions  could  not  cause  sufficient  change  to  account  for  the  flow 
known  to  occur  in  neves.  The  considerations  here  suggested  will  be 
again  referred  to  in  connection  with  certain  "  molecular  hypotheses  "  that 
have  been  proposed  to  account  for  glacier  flow. 

From  the  considerations  offered  above  it  seems  evident  that  the 
hypothesis  suggested  by  Moseley  cannot  be  accepted  as  a  final  explana- 
tion of  the  flow  of  glaciera. 

It  is  equally  plain,  however,  that  it  does  contain  an  element  of  truth, 
since  it  cannot  be  denied  that  ice,  like  most  other  substances,  does  contract 
and  expand  with  changes  of  temperature,  or  that  glaciers  are  exposed  to 
cc^xditions  which  bring  sibout  such  changes.  Some  fraction  of  glacier 
motion  must,  therefore,  be  due  to  those  causes. 


The  Hypothesis  of  Liquefaction  under  Pressure.  —  The  fact  that 
the  freezing-point  of  water  is  lowered  by  pressure,  discovered  by  James 
Thompson^  and  confirmed  by  his  brother  William,^  was  at  once  applied  in 
explanation  of  glacier  motion. 

As  stated  in  the  papers  just  referred  to,  if  ice  at  32°  F.  is  subjected 
to  pressure,  pores  occupied  by  liquid  water  must  instantly  be  formed  in 
the  compressed  parts,  for  the  reason  that  ice  cannot  exist  at  the  above  tem- 
perature under  a  pressure  exceeding  one  atmosphere.  If  the  conditions 
permit,  the  water  formed  by  the  melting  of  the  parts  under  pressure  Avill 
be  forced  to  where  the  pressure  is  less  and  at  once  refreeze.  The  parts 
recongealed  after  being  melted  must  in  turn,  through  the  yielding  of 
other  parts,  receive  pressure  from  the  applied  force,  thereby  to  be  again 
liquefied  and  to  enter  again  into  a  similar  cycle. 

In  applying  this  principle  to  glaciers  it  is  claimed  that  the  water 
formed  by  liquefaction  may  in  part  descend,  and  on  re  freezing  occupy  a 
lower  position.  (It  might  be  asked,  however,  why  the  water,  if  under 
pressure,  should  descend  rather  than  move  in  any  other  direction.)  A 
continuation  of  this  process,  it  must  be  admitted,  would  tend  to  crowd  an 
alpine  glacier  down  the  valley  it  occupies,  but  the  amount  of  movement 
thus  produced  would  be  small. 

In  opposition  to  this  hypothesis  it  is  evident  that  the  greatest  pressure, 
at  least  in  the  case  of  a  glacier  flowing  through  an  even  channel,  is  at  the 
bottom,  Avhile  the  surface  sustains  the  pressure  of  only  one  atmosphere, 

* "  On  the  Plasticity  of  Ice,  as  manifested  in  Glaciers,"  Roy.  Soc,  Proc,  vol.  8,  1867,  pp. 
455-468.  "  On  Recent  Theories  and  Experiments  regarding  Ice  at  or  near  its  Melting-point," 
Roy.  Soc,  Proc,  vol.  10,  1859,  pp.  152-160. 


HOW   AND    WHY   GLAGIEHS    MOVE. 


179 


and  in  the  great  majority  of  cases  of  less  than  one  atmosphere,  yet  the 
maximum  flow  is  always  at  the  surface.  Additional  weight  is  given  to 
this  objection  when  we  recall  the  fact  that  the  flowing  motion  observed 
in  glaciers  is  greatest  at  the  surface  even  in  cold  weather ;  at  such  times 
the  surface  ice  may  reasonably  be  concluded  to  have  a  lower  temperature 
than  the  bottom  ice,  and  therefore  require  a  greater  amount  of  pressure 
to  cause  it  to  liquefy. 

It  does  not  seem  as  if  further  argument  was  necessary  to  show  that  the 
lowering  of  the  melting-point  of  ice  by  i)ressure  does  not  furnish  a  com- 
plete and  satisfactory  explanation  of  glacier  motion  ;  but  that  it  may  play 
a  part  in  the  phenomena  for  which  an  explanation  is  sought,  especially  in 
the  case  of  excessively  thick  ice  bodies  or  of  glaciera  flowing  thnugh 
irregular  channels,  cannot  be  refuted. 


The  H5T>othesis  of  Molecular  Change.  —  An  ingenious  and  highly 
suggestive  hypothesis  advanced  by  James  Croll  to  account  for  the  flow  of 
glaciers  is  based,  in  part,  oi>  the  well-known  fact  that  water  in  freezing 
gives  out  heat  and  expands  on  passing  to  the  solid  state  ;  and  conversely, 
when  ice  melts  heat  is  absorbed,  and  in  passing  to  the  liquid  state  occupies 
less  space  than  before  the  change.  The  difference  in  volume  between  ice 
at  32°  F.  and  the  water  formed  from  its  melting,  at  the  same  temperature,  is 
about  one-tenth,  that  is,  the  ice  occupies  one-tenth  more  space  than  the  water. 

Another  principle  that  entere  into  this  hypothesis  is  that  heat  above 
32°  may  be  transmitted  through  ice,  and  yet  the  ice  as  a  mass  remain 
solid.  This  has  been  demonstrated  by  T3'ndall  and  others  b}^  placing  a 
delicate  heat-measuring  apparatus  on  one  side  of  a  siab  of  ice  and  bringing 
heat  to  the  opposite  side.  It  may  thus  be  shown  that  some  of  the  heat 
will  pass  through  the  ice,  but  portions  of  it  are  retained  and  produce 
changes  within  the  mass.  As  demonstrated  by  Tyndall,  in  producing 
"  liquid  flowers  "  in  ice  by  p^issing  heat  through  it,  a  portion  of  the  interior 
of  the  mass  of  ice  may  be  melted  by  heat  that  passes  through  other 
portions  which  remain  solid. 

The  hypothesis  before  us  assumes  that  the  heat  of  the  sun  on  reaching 
the  surface  of  a  glacier  is  partially  expended  in  melting  its  surface,  and 
that  a  part  of  the  water  thus  formed  is  transferred  to  the  ice  below  and  is 
refrozen,  and  that  the  heat  liberated  melts  other  portions,  which  again  re- 
freeze,  aud  so  on.  The  essential  feature  of  the  hypothesis  is  that  the  heat 
which  enters  the  ice  directly  also  leads  to  molecular  changes,  which  cause 
the  ice  to  descend.     Molecules  of  ice  are  assumed  to  be  melted,  and  on 


180 


GLACIERS   OF   NORTH   AMERICA. 


refreezing  pass  Iheir  heat  to  other  molecules.  But  the  molecules  lique- 
fied occupy  less  space  than  before  melting  and  change  their  petition  in 
response  to  gravity  or  pressure,  and  on  refreezing  again  expand  and  exert 
a  force  on  their  confining  walls. 

In  the  hope  of  stating  this  hypothesis  more  definitely  I  will  use  C roll's 
own  words  :  "  Let  us  observe  what  takes  place,  say,  at  the  lower  end  of 
the  glacier.  A  molecule  A  at  the  lower  end,  say  at  its  surface,  receives 
heat  from  the  sun's  rays  ;  it  melts  and  in  melting  not  only  loses  its  shear- 
ing force  and  descend^  by  its  own  weight,  but  it  contracts  also.  B,  imme- 
diately above  it,  is  now,  so  far  as  ^  is  concerned,  at  liberty  to  descend,  and 
will  do  so  the  moment  that  it  assumes  the  liquid  state.  A  by  this  time 
has  become  solid  and  again  fixed  by  shearing  force,  but  is  not  fixed  in  its 
old  position,  but  a  little  below  where  it  was  before.  If  B  has  not  already 
passed  into  the  fluid  state  in  consequence  of  heat  derived  from  the  sun, 
the  additional  supply  which  it  will  receive  from  the  solidifying  of  A  will 
melt  it.  The  moment  that  B  becomes  fluid  it  will  descend  till  it  reaches 
A.  B  then  is  solidified  a  little  below  its  former  position.  The  same 
process  of  reasoning  is  in  a  similar  manner  applicable  to  every  molecule  of 
the  glacier.  Each  molecule  of  the  glacier  consequently  descends  step  by 
step  as  it  melts  and  solidifies,  and  hence  the  glacier,  considered  as  a  mass, 
is  in  a  state  of  constant  motion  downwards." 

The  heat  that  reaches  a  glacier,  as  stated  by  Croll,  is  (1)  from  the  sun, 
either  directly  or  through  the  medium  of  the  atmosphere,  rain,  etc. ;  (2) 
earth-heat  from  the  rocks  over  which  the  glacier  passes  ;  and  (3)  the  heat 
produced  by  friction.  Of  these,  it  seems  to  the  present  writer,  account 
need  oidy  be  taken  of  the  heat  derived  from  the  sun.  The  earth-heat  is 
certainly  small,  and  for  the  present  at  least  can  be  consideied  as  having  no 
practical  bearing  on  the  question  in  hand.  The  heat  of  friction,  if  the 
movements  of  a  glacier  are  caused  solely  by  the  molecular  changes  con- 
sidered by  Croll,  is  due  to  the  arrest  of  motion  produced  by  the  energy  of 
the  sun,  and  to  admit  it  as  a  source  of  energy  to  be  used  in  explaining 
glacier  movement  would  be  utilizing  the  same  energy  twice.  That  is,  if 
the  sun's  heat  produces  glacial  movement,  and  by  the  arrest  of  this  move- 
ment a  part  of  the  energy  which  caused  it  is  reconverted  into  heat,  which 
in  its  turn  causes  glacial  motion,  there  is  no  end  to  the  circle.  A  glacier 
would  then  be  an  example  of  perpetual  motion. 

The  above  is  confessedly  an  imperfect  statement  of  the  molecular 
hypothesis,  and  it  is  perhaps  unjust  to  suggest  obstacles  to  its  acceptance 
without  a  more  complete  presentation,  but  as  space  will  not  admit  of  this, 


HOW   AND   WHY   GLACIERS   MOVE. 


181 


ion  111 
I  exert 


I  must  refer  the  reader  to  doll's  papers  and  books  for  a  full  exposition  of 
his  case.^ 

Neglecting  the  j  urely  theoretical  discussion  of  the  manner  in  which 
the  molecules  of  ice  are  supposed  to  be  influenced  by  the  passage  of  heat 
through  it,  since  this  is  a  question  for  physicists,  let  us,  as  geographers, 
see  how  the  hypothesis  before  us  meets  the  actual  conditions  with  which 
we  are  familiar  from  field  observations. 

Assuming,  what  must  be  practically  true  so  far  as  this  hypothesis  is 
concerned,  that  all  the  heat  which  reaches  a  glacier  comes  from  the  sun,  it 
follows  that  the  energy  requisite  to  loosen  the  molecules  of  the  ice  and  to 
allow  gravity  to  act  in  the  manner  postulated,  can  only  be  transmitted  to 
the  glacier  w  len  a  thermometer  at  its  surface  at  the  point  where  the  heat 
enters  stands  above  32°  F.  The  higher  the  temperature  indica  .d  by  such 
a  thermometer  the  more  rapid  would  be  the  ice  movement.  Also,  from 
the  fact  that  a  large  amount  of  energy  is  consumed  in  changing  the 
molecular  condition  of  ice  before  it  can  melt  —  physicists  tell  us  that  the 
amount  of  heat  absorbed  by  ice  at  32°  F.,  in  changing  to  water  at  the  same 
temperature,  is  equal  to  ♦.he  amount  of  heat  required  to  raise  the  water 
thus  formed  from  32°  B'.  to  172° — it  follows  that  a  thermometer  at  the 
surface  of  a  glacier  would  have  to  rise  well  above  32°  F.  or  remain  some- 
v/hat  above  that  temperature  for  a  considerable  time  in  order  that  the  ice 
might  receive  the  requisite  amount  of  heat  to  initiate  the  process  described 
by  the  author  of  the  molecular  hypothesis. 

In  attempting  to  apply  this  hypothesis,  however,  we  are  met  at  the 
'  outset  with  the  conclusion,  not  yet  successfully  controverted,  that  the  in- 
ternal temperature  of  a  glacier  is  always  32°  F.  or  lower.  This  conclu- 
sion is  based  on  several  fiicts,  as  for  example  :  first,  direct  observations  show 
that  as  nearly  as  can  be  determined  the  internr.i  temperature  of  a  glacier 
in  summer  is  32°  F.  ;  second,  ice  in  melting  under  atmospheric  pressure 
changes  to  water  with  a  temperature  of  32°  F.,  and  a  mixture  of  ice  and 
water  has  this  temperature  ;  third,  a  mass  of  ice  in  contact  with  air  below 
32°  F.  will  have  its  temperature  lowered. 

Turning  now  to  a  typical  alpine  glacier  we  find  that  near  its  source  the 
temperature  of  the  air  in  contrast  with  it  is  always  low.  In  the  Mount 
St.  Elias  region  surface  melting  does  not  occur  at  elevations  in  excess  of 
about  13,000  feet.     Above  that  elevation  the  snow  is  always  light  and  dry. 

^ "  On  the  Physical  Cause  of  the  Motion  of  Glaciers."  Philosophical  Magazine,  vol.  38, 
1869,  pp.  201-200.  "Climate  and  Time,"  1876,  pp.  1160-1196.  Also,  "The  Great  Ice 
Age,"  by  James  Geilcie,  2d  ed.,  1877,  pp.  21-31. 


182 


GLACIEUS   OF    NOUTH    AMERICA. 


At  noon  on  a  cloudless  August  day,  at  an  elevation  of  14,000  feet  on  the 
side  of  Mount  St.  Elias,  I  found  the  teraperuture  of  the  snow  at  a  depth 
of  two  or  three  inciies,  where  the  surface  was  directly  exposed  to  the  sun, 
to  l)e  sixteen  degrees  below  freezing.  This,  it  must  be  remembered,  is  the 
most  favorable  condition  for  melting  that  occui-s  throughout  the  entire 
year  at  the  locality  referred  to.  At  night,  even  in  summer,  the  tempera- 
ture of  the  air  falls  far  below  freezing.  For  probably  nine  months  or 
more  each  year  the  temperature  of  the  snow  at  the  surface  of  the  neves  in 
the  St.  Elias  region  is  continuously  below  the  freezing-point.  It  is  im- 
possible to  see  how  under  these  conditions  the  molecular  hypothesis  can 
be  applied,  yet  it  is  in  regions  of  the  nature  referred  to  that  glaciers  have 
their  birth.  The  snow  accumulating  on  neves  must  move  downward  be- 
fore trunk  glaciers  can  be  formed,  but  if  the  flow  of  the  lower  portions  of 
glaciers  is  to  be  accounted  for  by  molecular  changes  the  same  explanation 
should  be  applicable  to  ndve  regions  as  well. 

In  some  respects  the  impressions  conveyed  by  what  is  stated  above  will 
be  incorrect,  for  the  reason  that  few  neves  are  so  circumstanced  that  melt^ 
ing  does  not  occur  on  them  during  a  portion  of  en  h  year.  I  shall  endeavor 
to  show,  however,  that  the  other  extreme  of  conditions  to  which  neves  are 
subjected  is  no  more  favorable  to  the  molecular  hypothesis.  As  is  well 
known,  the  surfaces  of  neves  for  a  large  part  of  each  year  are  composed  of 
light,  dry  snow.  The  consolidation  of  this  snow,  it  would  seem,  must  take 
place  before  a  pushing  force  of  the  nature  postulated  by  Croll  could  act 
efficiently  in  producing  a  flowing  rrovement  in  the  mass.  Consolidation 
cf  ndve  snow  does  not  occur  when  the  temperature  of  the  air  in  contact 
with  it  is  above  the  freezing-point,  as  it  is  then  partially  melted  and 
frequently  so  completely  saturated  with  water  as  to  be  soft  and  slushy, 
and,  many  times,  holds  shallow  lakes  in  depressions  of  its  surface.  No 
one  will  claim,  I  fancy,  that  a  mixture  of  snow  and  water  of  such  a  con- 
sistency that  one  will  sink  knee-deep  into  it  at  every  step  —  a  condition 
frequently  present  on  the  neve  of  Alaska  —  is  favorable  to  the  passage  of 
heat  through  it  so  as  to  produce  molecular  changes  in  the  ice  below. 

It  appears,  then,  that  the  surface  of  a  neve,  both  when  below  32°  F., 
or  when  it  is  open  and  porous,  and  when  it  is  exposed  to  a  greater  tempera- 
ture and  becomes  saturated  with  water,  is  unfavorable  for  the  transmission 
of  solar  energy.  Again,  the  surface  of  a  neve  is  renewed  each  winter,  and 
in  many  instances  by  summer  storms  as  well ;  and  at  such  times  is  at  32°  F. 
or  lower ;  and  when  surface  melting  is  in  progress  the  snow  is  saturated  with 
water  and  consequently  has  a  temperature  of  32°  F.,  hence  it  is  impossible 


i 


HOW  AND  WHY  GLACIERS  MOVE. 


183 


to  conceive  how  a  temperature  in  excess  of  32°  F.  could  be  transiuittod  to 
the  solid  ice  beneath  so  as  to  give  it  motion. 

Nor  are  the  ditliculties  in  the  way  of  applying  the  molecular  hypothesis 
confined  to  neve  regions.  The  portion  of  a  glacier  that  protrudes  below 
its  nevd  is  blanketed  with  snov.  in  winter ;  the  air  in  contact  with  it 
is  then,  also,  normally  below  freezing.  In  summer  the  surface  of  the 
ice  is  frequently  covered  with  a  porous,  coral-like  crust,  which  is  almost 
as  perfect  a  non-conductor  as  dry  snow ;  and  when  this  crust  is  in  process 
of  melting  it  is  saturated  with  water  and  consequently  has  a  general  tem- 
perature of  32°  F.,  and  will  not  allow  heat  in  excess  of  that  temperature 
to  pass.  Glaciers  are  also  frequently  covered  more  or  less  completely 
with  moraines,  which,  when  over  a  few  inches  in  thickness,  still  more 
effectually  shield  the  ice  beneath  from  solar  energy.  When  we  consider 
the  nature  of  the  surface  preseiited  by  a  glacier  from  its  clear-white,  s^ow- 
covered  neve  to  its  dark  and  frequently  moraine-covered  terminus,  it  is 
apparent  that  the  positions  where  hard,  blue  ice  is  exposed  to  the  sky  are 
relatively  few.  It  may  be  said  in  general  that  clear  ice  is  only  exposed 
for  any  considerable  time  when  its  surface  gradient  is  sufficient  to  insure 
the  quick  escape  of  the  Avater  formed  by  superficial  melting.  Under  the 
molecular  hypothesis,  other  conditions  being  the  same,  motion  should  be 
most  rapid  where  the  surface  of  a  glacier  is  composed  of  clear  ice.  So  far 
as  now  known  observations  do  not  harmonize  with  this  postulate. 

Although  heat  may  be  transmitted  through  ice  in  laboratory  experi- 
ments and  cause  melting  within  its  mass,  yet  the  conditions,  as  shown 
above,  wlien  this  can  occur  in  the  case  of  glaciers  are  so  infrequent  that 
the  application  of  this  principle  in  explanation  of  glacier  motion,  even 
if  we  knew  the  nature  of  the  molecular  changes  that  occur,  meets  what 
seem  insuperable  difficulties. 

The  Hypothesis  of  Granular  Change.  —  Recent  observations  on  the 
structure  of  certain  Greenland  glaciers  by  T.  C.  Chamberlin  ^  have  led 
him  to  conclude,  as  previously  noted,  that  they  behave  as  rigid  rather  than 
as  plastic  bodies.  The  impression  gained  was  that  the  ice  is  thrust  for- 
ward by  an  expansive  force  acting  from  within  rather  than  pulled  by 
gravity  alone  after  the  manner  of  plastic  substances.  In  seeking  for  an 
explanation  of  glacier  flow  with  this  idea  in  mind  Chamberlin  again  di- 
rected attention  to  the  changes  which  occur  in  the  granulation  of  glacier 
ice  when  traced  from  its  source  to  the  extremity  of  a  glacier,  and,  as  others 

1"  Recent  Glacial  Studies  in  Greenland,"  Geol.  Soc.  Am.,  Bull.,  vol.  6, 1895,  pp.  109-220. 


i 

1 

) 

'1 

1 
-    \ 

184 


GLACIERS   OF    NOHTU    AMEUICA. 


have  done,  Huggested  that  the  principal  cause  of  movement  may  lie  in  the 
growth  of  the  granules.  Through  a  process  of  partial  melting  and  re- 
freezing  it  is  assumed  that  a  granule  may  continually  change  its  shape  hy 
loss  in  one  part  and  gain  in  another,  and  thus  either  move  itself  or  permit 
motion  in  a  neighbor.  To  bring  about  this  change  the  author  states  that 
"  every  warm  day  sends  down  into  the  glacier  a  wave  of  heat  energy,  sen- 
sible or  i)otential,  and  that  every  night  sends  after  it  a  wave  of  reverse 
energy.  These  waves  follow  each  other  indefinitely,  until  by  intercurrent 
agencies  they  become  vanishing  quantities.  Each  season  sends  through 
the  mass  a  greater  and  more  complex  wave.  The  problem,  therefore,  in 
simplified  form  postulates  a  mass  of  ice  granules  predisposed  to  melt  at 
certain  points  and  to  freeze  or  to  promote  freezing  at  others,  acted  upon 
by  the  ever-present  but  differential  forc*^  of  gravity  and  swept  by  succes- 
sive waves  of  heat  energy  competent  to  cause  melting  where  predisposition 
to  melting  exists  and  to  cause  growth  by  freezing  where  predisposition  to 
freezing  exists.  Out  of  this  it  would  seem  that  localized  freezing  and 
thawing,  growths  and  decadences,  innumerable  and  constantly  changing, 
must  result,  and  with  thc/n  motion  of  the  granules  themselves  and  of  the 
common  mass." 

Although,  in  fairness  to  my  readers,  I  must  confess  that  I  am  unable 
to  discuss  either  the  molecular  hypothesis  or  the  recent  modification  of  it 
from  the  standpoint  of  the  physicist,  yet  the  adverse  bearing  of  certain 
facts  on  these  hypotheses  and  difficulties  in  the  way  of  applying  them 
to  explain  well-known  glacial  phenomena  suggest  themselves  even  to  a 
layman. 

Present  knowledge  of  the  physical  properties  of  ice  and  of  water  seems 
to  show  that  when  they  are  in  contact  at  the  same  temperature,  at  least 
when  not  under  pressure  exceeding  one  atmosphere,  there  is  no  reason  to 
suppose  that  there  would  be  a  mutual  change  of  condition.  That  is,  so 
far  as  I  am  aware,  there  is  no  reason  to  suppose  that  a  molecule  of  water 
at  32°  and  a  molecule  of  ice  at  the  same  temperature,  placed  side  by  side, 
would  undergo  a  mutual  interchange  of  their  physical  properties,  the 
water  becoming  ice  and  the  ice  changing  to  water.  But  this  seems 
to  be  an  essential  feature,  although  not  stated  in  these  words,  of  both 
the  molecular  hypothesis  and  the  modified  version  of  it. 

Another  consideration  is  that  molecular  changes  postulated  cannot  take 
place  in  ice  that  is  bslow  32°  F.  unless  pressure  is  greatly  increased.  If 
pressure  is  the  controlling  condition,  then  the  movements  supposed  to  occur 
would  increase  with  depth  of  ice,  and  the  bottom  of  a  glacier  should  flow 


HOW   AND    WIIV    GLACIERS    MOVE. 


185 


more  rapidly  than  its  surface.  This,  we  know,  is  the  opposite  of  what 
really  does  take  i)lace. 

Chan)berlin  speak,  of  waves  of  sensible  or  potential  heat  energy  pass- 
ing through  a  glacier  every  warm  day,  but  it  is  to  Im)  remeniljered  that 
warm  days  on  the  upper  portions  of  glaciei-s,  especiall}',  are  mre  ;  and,  as 
already  pointed  out,  the  n6v6  of  a  glacier  is  constantly  blankoted  by  a 
non-conducting  layer  such  as  no  wave  of  sensible  heat,  at  least,  can 
penetrate. 

The  explanation  suggested  by  Chaml)erlin,  like  its  predecessor,  is 
based  on  theoretical  deductions  which  have  not  l)een  proven.  Before 
claiming  that  solar  energy  causes  motion  in  glaciers  by  the  melting 
and  refreezing  of  molecules,  or  by  changes  in  the  size  and  shape  of 
granules,  it  would  be  more  consistent  to  determine  if  these  changes  do 
occur  in  ice  under  the  most  favorable  conditions.  But  even  if  it  could  be 
shown  that  a  "  wave  of  heat  energy,  sensible  or  potential,"  could  lead  to  a 
change  in  the  form  and  size  of  granules,  the  ssime  objections  to  the  trans- 
fer of  such  energy  from  the  surface  to  the  inner  positions  o^  a  glacier, 
suggested  in  reference  to  Croll's  hypothesis,  would  have  to  be  met. 

While  it  is  apparently  impossible  to  demonstrate  that  the  changes  in 
ice  assumed  by  Croll  and  Chamberlin  do  not  tako  place,  it  is  logical  to 
wait  until  sufficient  reasons  have  been  advanced  to  prove  that  they  do 
occur  even  under  the  most  favorable  conditions,  before  making  the 
assumption  the  basis  of  a  still  more  extended  hypothesis.  At  present  the 
postulates  on  which  the  molecular  hypothesis  and  its  recent  modification 
rest,  may  be  said  to  be  in  the  hands  of  the  physicist  If  their  truth  is 
ultimately  demonstrated,  they  may  be  passed  on  to  the  geologist  and 
geographer  to  be  tested  as  a  means  of  explaining  glacial  motion. 

What  seems  intended  as  a  modification  of  the  molecular  hypothesis 
has  been  proposed  by  R.  M.  Deeley  ^  and  can  be  studied  with  profit,  but 
80  far  as  I  have  been  able  to  determine  it  does  not  differ  materially  from 
the  explanation  proposed  by  Croll. 


Conclusion. 

From  the  brief  account  given  above  of  various  hypotheses  that  have 
been  advanced  to  account  for  the  movement^'  of  glaciers,  it  will  be  seen 
that  no  one  of  them  meets  all  the  conditions  of  the  problem.  No  one  ex- 
planation has  been  generally  accepted,  although  the  hypothesis  of  plas- 

i"A  Theory  of  Glacial  Motion,"  Philosophical  Magazine,  vol.  25,  1888,  pp.  130-164. 


186 


OLACIEKH   UF    NORTH    AMEUICA. 


ticity  i)rol)iil)ly  has  more  sidhereiitH  than  any  other.  From  what  hiw  l)eeii 
Htatetl,  however,  I  think  it  will  appear  that  several  of  the  explanations 
offered  are  hased  on  one  or  more  well-e.stablinhed  laws  and  furnish  an 
explanation  of  some  phase  of  glacial  motion.  Even  the  earliest  and  lonu. 
since  abandoned  hypothesis  of  Charpentier,  which  iwsumes  that  glaciers 
slide  as  rigid  bodies  over  their  betls,  contains,  as  we  have  seen,  an  element 
of  truth.  If  this  can  Ik;  said  of  the  crudest  of  all  the  exj)lanation.s 
advanced,  the  later  and  more  elaborate  hypotheses  should  certainly  not 
be  discarded  without  careful  scrutiny  in  order  to  obtain  from  tli  jni  all  the 
assistance  ia  arriving  at  a  linal  theory  that  is  possible.  To  the  discredit 
of  men  of  science,  it  must  be  acknowledged,  that  in  discussing  the  problem 
of  glacier  motion,  the  practice  has  too  frecjue'^^'y  i)revailed  of  rejecting  all 
previous  hypotheses  in  order  to  make  room  for  some  newer  idea.  The 
attitude  of  scientific  men  in  this  connection  has  freciuently  been  that  of 
an  advocate  pleading  for  his  client,  rather  than  a  judicial  balancing  of 
evidence. 


An  Eclectic  HMiotlicsis.  —  The  review  just  attempted  leads  to  at  least 
one  conclusion  which  seems  well  founded.  That  is,  the  phenomena  to  be 
accounted  for  are  complex,  and  no  single  law  governing  the  behav  of  ice 
can  be  made  to  ex^^lain  all  phases  of  glacier  motion. 

The  principal  laws  and  the  leading  physical  properties  of  ice  which  are 
c  neerned  in  modifying  the  form  of  glaciers  at  one  time  or  another,  or  at 
on«^  locality  or  another,  may  be  briefly  enumerated  as  follows  : 

1.  Gravity  is  ever  present  and  tends  continually  to  change  the  form 
of  a  glacier.  This  fundaraentil  fact  is  recognized  in  every  hypothesis  that 
has  been  advanced. 

2.  Ice,  although  brittle  under  a  force  quickly  applied,  yields  con- 
tinuously under  its  own  Aveight  to  both  pressure  and  tension  in  a  dimin- 
ishing ratio  from  32°  F.  to  lower  temperatures. 

3.  Fragments  of  ice  when  brought  in  contact  at  or  near  a  tempera- 
ture of  32"  F.  will  freeze  together,  but  without  pressure  this  does  not 
occur  at  lower"  temperatures. 

4.  Water  expands  on  freezing,  the  increase  in  volume  being  about 
one-tenth.     The  converae  is  also  true. 

5.  Water  held  in  fissures  or  in  the  interetices  of  glaciers  exei-ts  a 
hydraulic  pressure,  and  ol^eys  the  laws  governing  capillary  attraction. 

6.  Ice  like  other  solids  expands  and  contracts  with  changes  of 
temperature. 


HOW  AND   WHY   OLACIEU8   MOVE. 


187 


7.  Heat  can  be  made  to  piws  tlirough  ice,  as  shown  by  Tyndall,  and 
portions  of  the  ice  may  Iw  melted  by  heat  that  has  pauiied  tluuugh  other 
portions  without  producing  visible  clianges. 

8.  The  melting-point  of  ice  is  hiwered  by  pressure. 

9.  A  mixture  of  ice  and  water  under  a  pressure  not  exceeding  one 
atmospliere  lias  a  temperature  of  32°  F. 

10.  Ice  (.'1  melting  absorlw  heat.       Water  on  freezing  gives  out  heat. 

11.  The  tenjperature  of  ice  is  raised  by  compression  and  lowered  by 
tension. 

Other  laws  may  l)e  added  to  this  list,  but  at  present  those  enumemted 
seem  to  be  the  princi{)al  ones  that  can  be  applied  in  solving  the  question 
of  the  causes  of  glacier  motion. 

The  phenomena  exhibited  by  glaciers  for  which  explanation  is  sought 
may  also  be  briefly  enumerated  : 

1.  Glaciei-s  exhibit  a  v/ell-defined  flowing  movement,  analogous  to 
the  flow  of  plastic  substances. 

2.  The  flow  of  a  glacier,  best  illustrated  by  one  of  the  alpine  type, 
is  greatest  in  the  center  and  at  the  surface,  and  decreases  toward  the  sides 
and  bottom.     That  is,  it  is  analogous  t<   i  he  flow  of  a  river. 

3.  The  flow  is  greater  in  summer  than  in  winter,  and  greater  by  day 
than  by  night.  That  is,  it  varies  in  harmony  with  changes  in  ptmospheric 
temperature,  and  is  greatest  when  the  temperature  is  highest.  More  than 
this,  observations  have  shown  that  changes  in  the  rate  of  flow  respond 
with  considerable  promptness  to  changes  of  temperature. 

4.  The  movements  of  any  given  point  in  a  glacier  are  not  uniform  in 
any  one  direction,  but  vary  from  hour  to  hour.  In  the  case  of  an  alpine 
glacier  so  far  as  has  been  observed,  the  algebraic  sum  of  the  movements 
by  day  are  in  the  direction  of  descent,  while  at  night  there  may  be  a 
resultant  displacement  toward  the  mountain  from  which  the  glacier  flows. 

5.  Motion  occui's  both  in  neve  regions  and  in  the  glacier  proper,  and 
so  far  as  known  is  of  the  same  nature  in  each  instance ;  but  more  extended 
studies  la  this  connection  are  desired. 

6.  The  mean  rate  at  which  a  glacier  flows  is  not  the  same  in  different 
portions  of  its  course.  That  is,  for  example,  the  avertige  rate  of  move- 
ment of  all  points  in  a  given  cross  section  may  vary  widely  from  a  similar 
average  in  another  cross  section. 

7.  When  the  grade  of  a  valley  through  which  a  glacier  flows  changes 
abruptly,  or  when  its  bottom  or  sides  are  markedly  irregular,  the  ice 
becomes  broken  and  crevassed.     Tension  is  also  produced   under  other 


188 


GLACIERS    OF    NORTH    AMERICA. 


conditions,  as  when  a  glacier  expands  on  a  plain,  and  rissures  are  again 
formed. 

3.  Glacial  ice  alwunds  in  fissures  and  interstices  which  are  usually 
filled  witli  water.  Near  the  surface  the  water  held  in  Ihis  manner  fre- 
quently freezes  at  night.  The  effect  of  winter  temperatures  must  be  felt 
to  a  still  greater  cle})th,  but  how  deep  has  not  been  determined.  Water 
flows  from  beneath  the  extremity  of  nearly  eveiy  alpine  glacier,  even  in 
winter,  and  to  a  great  extent  represents  the  drainage  of  the  ice.  Evidently 
the  fall  of  temperature  in  winter  is  not  sufficient,  or  not  long  enough  con- 
tinued, to  congeal  all  the  water  that  enters  the  ice  during  the  summer  season. 

9.  Glacial  ice  is  granular.  Nev6  snow  is  also  granular.  As  shown 
by  Heini,  however,  the  granules  of  the  n6v6  are  distinct  and  of  a  different 
nature  from  the  granules  of  glacier  ice.  In  the  glacier  proper  the  granules 
increiise  in  size  from  near  the  neve  to  its  extremity.  In  restricted  areas 
the  granules  are  of  approximately  the  same  size,  large  and  small  grains  not 
being  intermingled. 

10.  When  glacial  ice  is  broiven,  as  when  crevasses  are  formed,  and  the 
fragments  brought  in  contact,  they  refreeze. 

11.  The  rocks  over  which  glaciera  move  become  worn  and  striated. 
Hard  nodules  in  glaciated  rocks  are  frequently  left  in  relief.  "  Chatter 
marks,"  semi-lunar  cracks,  etc.,  also  occur  on  surfaces  but  recently  aban- 
doned by  a  receding  glacier. 

12.  Rock  basins  but  recently  vacated  by  glacier  ice  are  smoothed  and 
striated  within,  showing  that  debris-charged  ice  descended  into  them  i=o 
as  to  wear  their  surfaces. 

13.  Debris  contained  in  a  glacier  tends  to  decrease  its  rate  of  flow. 
If  we  conceive  of  a  glacier  compound  of  clear  ice  moving  at  a  given  rate 
and  introduce  debris  —  earth,  sand,  stones,  boulders,  etc.  —  into  it,  with- 
out altering  other  conditions,  the  effect  will  be  to  decrease  the  rate  of 
flow,  since  rigid  substances  are  added  to  one  having  properties  that  are 
at  lesist  analogous  to  those  of  a  plastic  solid.  If  we  gradually  increase 
the  percentage  of  debris,  the  mass  will  become  less  and  less  mobile,  and 
finally  acquire  such  rigidity  that  under  the  conditions  normally  influen- 
cing the  movements  of  glaciers  it  will  cease  to  flow.  If  the  debris,  instead 
of  being  uniformly  commingled  with  the  ice,  is  introduced  irregularly, 
local  changes  in  the  rate  of  flow  and  even  local  stagnation  will  result.^ 

1  The  influence  of  debris  on  the  flow  of  glaciers,  based  on  the  assumption  that  ice  is  plastic 
and  when  in  sufficiently  large  inass'^s  will  flow  under  the  influence  of  its  own  weight,  has  been 
discussed  by  the  author  in  The  Journal  of  Geology  [Chicago],  vol.  3,  1896,  pp.  823-832. 


T^ 


HOW  AND  WHY  GLACIEKS  MOVE. 


189 


This  list  of  facts,  bearing  more  or  less  directly  on  the  cliaracter  of  the 
movements  that  take  place  in  glaciers,  and  thus  furnishing  data  for  test- 
ing proposed  explanations  of  their  movements,  might  be  extended,  but  I 
believe  that  the  most  suggestive  observations  now  in  hand  have  been 
enumeiated. 

By  codifying  the  Ipavs  governing  the  behavior  of  ice  under  various 
conditions,  and  grouping  the  phenomena  related  more  or  less  directly  with 
glacial  flow,  in  the  manner  just  attempted,  it  will  appear,  I  think,  that 
the  mo^  jments  of  glacial  ice  are  more  complex  than  has  commonly  been 
stated,  and  are  due  at  different  times  and  under  different  conditions  to 
diff3rent  agencies,  or  to  the  interaction  of  various  agencies. 

Of  the  forces  to  which  glaciei-s  are  exposed  which  tend  to  change 
their  shapes,  gravity  is  the  only  one  that  acts  continually  and  always  in 
the  same  direction.  The  fact  that  ice,  as  shown  by  careful  experiments, 
will  change  its  shape  under  the  influence  of  its  own  weight  at  all  temper- 
atures from  a  maximum  rate  at  32°  F.  as  far  below  as  tests  have  been 
carried,  and  yields  continuously  to  tension  as  well  as  to  pressure,  is  strong 
evidence  favoring  the  assumption  that  glaciers  descend  or  flow  in  a 
manner  analogous  to  the  flow  of  plastic  bodies.  Supplementing  this 
cause  of  glacier  motion,  although  apparently  in  most  instances  of  minor 
importance,  is  the  hydrostatic  pressure  of  water  enclosed  in  glacial  ice  ; 
dilatation  of  water  in  freezing  in  fissures ;  expansion  and  contraction  of 
the  ice  with  changes  of  temperature  ;  melting  and  refreezing,  due  to 
changes  in  pressure  ;  regelation ;  and,  less  clearly,  molecular  changes 
caused  by  the  transmission  of  heat,  and  the  melting,  refreezing,  and 
growth  of  granules. 

The  authors  of  this  eclectic  hypothesis  may  be  considered  to  l)e  De 
Saussure,  Charpentier,  Agassiz,  Forbes,  Rendu,  Guyot,  Tyndall,  Thompson, 
Croll,  Geikie,  Heim,  Helmholtz,  Moseley,  McConnel,  Chan^berlin,  and  in 
fact  all  physicists  and  glacialists  who  either  directly  or  indirectly  have 
contributed  to  the  study  of  glacial  dynamics.  More  than  this,  the  study 
of  the  physical  properties  of  ice  and  the  application  of  principles  already 
known  or  to  be  discovered  in  explanation  of  glacier  movements,  is  not 
yet  completed.  To  the  list  of  distinguished  names  given  above,  as  the 
authors  of  the  "eclectic  hypothesis,"  are  to  be  added  the  names  of  those 
who  in  the  future  make  contributions  to  our  knowledge  of  the  properties 
of  ice  and  of  its  behavior  under  various  conditions.  The  new  facts  and 
new  principles  discovered  are  to  be  included  in  this  hypothesis,  which 
will  thus  continue  to  be  an  illustration  of  the  evolution  of  ideas. 


CHAPTER  X. 


THE   LIFE   HISTORY  OP  A  GLACIER. 

Glaciers,  like  streams  and  lakes,  valleys  and  mountains,  have  their 
periods  of  youth,  adolescence,  maturity,  and  old  age,  leading  to  extinction. 
Like  the  snows  of  winter  they  come  and  go  in  obedience  to  unseen  forces. 
Their  growth  and  decline  may  embrace  thousands  and  even  tens  of 
thousands  of  years,  but  even  the  longest-lived  witness  but  a  portion  of 
the  changes  in  topographical  development  to  which  they  lend  their  aid. 
The  study  of  existing  ice  bodies  leads  backward  step  by  step  to  the  far 
greater  ice  sheets  of  the  glacial  epoch.  Although  the  causes  that  pro- 
duced vast  continental  glaciei-s  in  comparatively  recent  geological  times 
are  not  well  undei-stood,  and  have  been  a  fruitful  source  of  controversy, 
yet  when  one  has  in  mind  the  life  history  of  a  single  existing  glacier,  it 
becomes  evident  that  former  periods  of  extensive  glaciation  were  but 
greater  steps  in  the  same  direction.  Methods  of  study  are  thus  indicated, 
and  suggestions  obtained  for  attacking  unsolved  problems  in  the  history 
of  the  earth. 

As  a  beginning  in  this  broad  field  of  exploration,  let  us  endeavor  to 
obtain  a  graphic  idea  of  the  changes  made  manifest  in  the  birth,  growth, 
decline,  and  death  of  a  single  alpine  glacier. 

The  snow  line  —  the  lowest  limit  of  perennial  snow  —  may  be  said  to 
have  its  position  determined  by  the  intersection  of  the  earth's  surface  with 
an  invisible,  hollow  spheroid  of  temperature.  This  invisible  spheroid 
may  for  present  purposes  be  f  tncied  to  pass  through  all  points  having  a 
mean  annual  temperature  of  32°  F.  In  the  tropics  it  is  some  18,000 
feet  above  the  sea,  but  decreases  in  elevation  toward  either  pole.  In 
high  latitudes,  it  may  pass  below  the  earth's  surface.  Its  size  and  form 
change  in  obedience  to  many  far-reaching  and  frequently  antagonistic 
agencies,  and  is  never  the  same  for  two  consecutive  years  or  for  any 
two  terms  of  years  that  may  be  selected.  It  is  modified  from  within 
by  changes  in  the  inherent  heat  of  the  earth,  in  movements  producing 
elevations  and  depressions,  in  the  distribution  of  land  and  water,  in  the 
direction  and  character  of  ocean  currents,  in  the  movements  of  the  atmos- 
phere, in  the  distribution  of  vegetation,  in  topographic  relief,  and  in  other 


THE  LIFE   HISTORY   OF  A   GLACIER. 


191 


ways.  It  is  modified  from  without,  principally  by  annual  and  secular 
changes  in  the  amount  of  heat  that  reaches  the  earth  from  the  sun  due  to 
changes  in  the  position  of  the  earth,  the  inclination  of  the  earth's  axis, 
and  perhaps  other  causes. 

When  one  endeavors  to  marshal  in  fancy  the  interaction  of  the  various 
conditions  on  which  the  fluctuations  of  the  snow  line  depend,  the  wonderful 
complexity  of  glacial  problems  is  suggested.  The  difficulties  to  be  over- 
come are  still  farther  increased  when  one  recalls  the  fact  that  while 
glaciers  do  not  originate  when  the  mean  ainiual  temperature  is  above  32°, 
they  may  not  form  when  that  limit  is  reached,  unless  still  other  conditions, 
as  an  abundance  of  snow,  alternations  of  warm  and  cold  seasons,  etc.,  are 
fulfilled. 

Could  we  tint  the  ever-changing  surface  of  the  spheroid  of  32°  as  the 
student  who  uses  the  microscope  sometimes  tints  the  walls  of  the  cells  he 
examines,  and  view  the  earth  from  a  distance,  its  pulsations  in  obedience 
to  the  many  forces  on  which  its  size  and  form  depend  would  be  manifest. 
Under  those  conditions,  were  time  allowed,  the  various  steps  in  the 
gathering  of  perennial  snows,  the  birth  and  growth  of  glaciers,  and  the 
coming  and  going  of  geological  winters  could  be  followed. 

This  fancied  view  of  the  working  of  a  single  part  of  the  complicate 
machinery  we  term  climate,  is  not  intended  to  lead  to  a  discussion  of  the 
ultimate  causes  of  glacial  conditions,  but  merely  to  invite  the  reader  to 
cut  loose  from  ideas  of  days  and  years,  and  view  the  growth  and  decline  of 
a  glacier  which  numbers  centuries  in  its  life-span. 

The  histories  of  the  three  main  class  ;  of  glaciers  usually  recognized  are 
not  the  same  but  have  many  features  in  common.  Individual  examples 
of  each  class  require  such  a  length  of  time  tu  i  un  their  appointed  coui-ses, 
that  but  a  faint  idea  of  the  changes  they  undergo  can  be  gained  from  the 
study  of  a  single  example,  even  if  one  spent  an  average  lil>  ame  in  the 
task.  But  by  combining  observations,  made  in  various  regions,  on  glaciei-s 
that  have  reached  different  stages  in  their  development  or  decline,  the 
chief  episodes  in  the  life  history  of  a  typical  example  may  be  outlined. 
Let  us  climb  to  a  station  on  a  mountain-side,  overlooking  a  deen  valley 
that  leads  from  white  peaks  above  to  a  dark,  forest-covered  i)lain  below, 
and  v/atch  in  fancy  the  birth,  growth,  and  retreat  of  a  single  glacier  of  the 
alpine  type. 

The  life  of  an  alpine  glacier  usually  begins  when  a  mountain  summit 
pierces  the  splieroid  of  32°.  Whether  this  happens  on  account  of 
changes  in  the  lithosphere  or  in  the  spheroid   of   temperature,  or   by 


192 


GLACIEllS   OF   NORTH  AMERICA. 


I 


a  mutual  adjustment  of  the  two,  is  beyond  our  present  theme.  As 
the  mountain  peak  reaches  higher  and  higher  above  the  spheroid  of 
32°,  the  mantle  of  snow  drawn  about  its  summit  descends  lower  and 
lower.  Above  the  snow  line  the  winter's  snow  is  not  completely  melted 
during  the  succeeding  summer,  and  accumulates  from  year  to  year.  If 
the  mountain  was  sculptured  by  streams  before  the  postulated  change 
occurred,  or  is  irregular  for  other  reasons,  the  snow  will  be  blown  from 
the  peaks  and  ridges  and  accumulate  to  a  great  depth  in  the  depressions. 
The  head  of  a  valley  becomes  filled  in  this  manner  with  a  broad  snow 
field,  and  in  summer  the  mountain  seems  to  be  tipped  with  silver.  The 
snow  toward  the  bottom  of  the  accumulation  becomes  consolidated  by 
pressure.  Water  formed  by  surface  melting  percolates  through  it  and  is 
frozen.  The  lower  layers  are  thus  changed  to  ice,  and  a  neve  is  born. 
The  sr  ice  of  the  snow  field  is  softened  and  partially  melted  during  daj^s 
of  sunshine  or  when  warm  winds  blow  over  it,  and  freezes  at  night  or 
during  storms,  and  a  thin  crust  of  ice  is  formed.  Tliis  hard,  glittering 
layer  is  buried  beneath  the  next  succeeding  snowfall,  and  remains  as  a 
well-defined  stratum  in  the  growing  ne^'e.  In  the  walls  of  crevasses,  the 
tliin  sheets  of  ice  formed  in  this  way,  as  may  be  learned  from  a  near 
inspection,  appear  as  narrow  blue  bands  separating  layei*s  of  snow,  perhaps 
many  feet  thick.  Dust  blown  from  adjacent  peaks  and  cliffs  that  rise  above 
the  n^ve,  stains  its  surface.  The  discolored  layer  is  buried  beneath  subse- 
quent snowfalls,  and  again  accents  the  stratification  of  the  deposit. 

If  we  could  plant  a  row  of  signals  across  the  neve  at  right  angles  to  the 
trend  of  the  valley  down  which  its  surface  inclines,  we  should  find  in  the 
course  of  a  few  days,  or  even  in  a  few  liours,  if  our  observations  were 
sufficiently  refined,  that  there  is  a  slow  surface  movement,  greater  in  the 
central  and  lower  portion  and  tending  down  the  valley.  Could  we  make 
similar  measurements  in  a  vertical  direction  where  the  surface  movement 
is  greatest,  we  should  find  that  the  maximum  flow  is  below  the  surface, 
and  probably  near  the  bottom  of  the  deposit.  That  the  rate  of  movement 
increases  with  the  depth  and  reaches  a  maximum  near  the  bottom,  is 
only  an  inference  from  the  study  of  superficial  phenomena,  and  has 
never  been  proven  by  direct  measurements.  In  the  glacier  proper 
the  threads  of  most  rapid  flow  are  known  to  be  at  a  higher  level  in 
reference  to  the  basement  layer  than  is  supposed  to  be  the  case  in  the 
neve  ;  accompanying  this  apparent  change  in  the  position  of  the  line 
of  greatest  movement  are  important  modifications  in  the  behavior  of 
the  flowing  body. 


THE   LIFE    HISTORY   OF   A   GLACIER. 


193 


The  surface  snow  of  the  n6v6  is  carried  along  by  the  more  rapid  move- 
ment of  the  consolidated  portion  deep  below,  and  great  breaks  are  formed 
at  the  base  of  the  encircling  cliffs  owing  to  the  surface  snow  being  moved 
away  from  them.  These  breaks,  in  which  the  rocks  beneath  are  frequently 
exposed,  are  conspicuous  from  a  distanea.  As  we  watch  the  slow  growth 
of  the  glacier,  we  note  in*  the  course  of  centuries,  that  the  amphitheatre 
from  which  it  flows  becomes  gradually  enlarged,  its  walls  at  the  same  time 
increasing  in  steepness.  The  great  crevasses  on  the  upper  border  of  the 
i\e\6  are  filled  each  winter,  but  reopen  each  spring  in  about  the  same 
I^laces.  Observations  at  intervals  of  centuries,  however,  would  show  that 
their  positions  do  not  remain  the  same,  but  owing  to  the  waste  of  the 
rocks  exposed  each  summer  within  them,  a  slow  migration  toward  the 
crest  of  the  mountains  takes  place,  that  is,  the  cliffs  recede. 

As  the  neve  increases  in  thickness,  the  motion  of  the  deeper  layei"s  be- 
comes greater,  and  at  length,  in  late  summer  or  early  autumn,  a  protrusion 
of  solid  ice  is  seen  extending  out  from  beneath  its  lower  margin.  The 
flow  of  the  young  glacier  in  some  instances  is  so  energetic  that  the  n6xe 
field  from  which  it  is  fed  is  seemingly  in  danger  of  exhaustion.  At  times, 
comparatively  insignificant  n6ves  supply  ice  bodies  that  are  disproi^ortion- 
ately  large.  This  occurrence  seems  to  accompany  climatic  conditions  that 
are  unfavorable  to  surface  raqlting.  Possibly  the  \\jfcrkings  of  natural 
laws  in  this  connection  are  better  illustrated  by  young  glaciers  than  by 
more  aged  examples,  and  more  perfect  snow  drainage  is  secured  than  when 
the  ice  stream  below  becomes  congested  and  is  clogged  with  morainal 
material. 

The  young  glacier  advances  its  extremity  by  reason  of  the  more  rapid 
rate  of  flow  of  the  ice  near  the  surface  and  in  the  center  of  the  stream. 
In  this  way,  what  was  the  expanded  margin  of  the  ice  foot  at  any  indi- 
cated time,  becomes  covered  by  the  ice  thrust  forward  during  the  next 
period  of  marked  advance.  The  movement  being  greatest  In  summer 
and  least  in  winter,  there  is  an  annual  pulsation  of  the  slowly  advancing 
extremity.  There  are,  besides,  periodic  changes  of  similar  character  but  of 
greater  magnitude.  When  the  advance  of  the  extremity  of  the  glacier  is 
rapid,  the  onward  surface  flow  each  summer  buries  the  portion  remaining 
from  the  previous  summer  advance.  Debris  carried  on  the  surface  of  the 
glacial  stream  thus  becomes  transferred  to  the  bottom  layer.  Moraines 
deposited  in  front  of  the  advancing  glacier  during  one  summer  become 
buried  by  the  advancing  terminus  during  the  next  succeeding  summer, 
and  are  added  to  the  ground  moraine.     Like  results  follow  also  from 


194 


GLACIERS   OF   NORTH   AMERICA. 


similar  periodic  changes  of  greater  magnitude.  Owing  to  the  manner  of 
its  advance,  the  terminus  of  a  young  glacier  is  steep.  The  frontal  slope 
is  generally  higher  and  bolder  than  during  old  age,  when  the  terminus  is 
receding,  but  this  is  not  always  the  case. 

From  our  fancied  station  overlooking  a  valley  down  which  a  young 
glacier  has  begun  its  journey,  and  where  also  in  fancy  centuries  are  but 
as  hours,  we  see  other  similar  streams  of  ice  descending  tributary  valleys 
and  entering  the  main  avenue  of  drainage. 

The  roar  of  avalanches,  especially  after  heavy  snowfalls,  as  they  plow 
their  way  down  the  mountain-side,  awakens  the  echoes  as  if  heavy  guns 
had  been  discharged.  The  rushing  snow  masses  carry  with  them  dirt, 
stones,  and  occasionally  large  rock  masses,  and  assist  in  the  formation  of 
lateral  moraines  along  the  borders  of  the  glaciers.  When  an  interval  of 
sunshine  loosens  the  icy  bands  with  which  the  shattered  cliffs  are  bound, 
stones  break  away  and  join  the  rubbish  piles  below.  Again,  when  the 
shadows  of  evening  fall  on  the  cliffs  and  the  temperature  is  lowered  below 
the  freezing-point,  additional  blocks  of  stone  pried  off  from  the  faces  of 
precipices  are  shot  downward  with  a  shrill,  whistling  sound,  and  bury 
themselves  in  the  soft  snow  below  or  strike  with  a  dull  thud  on  the  hard 
ice.  We  can  see  many  localities  where  the  ice  and  snow  adjacent  to  the 
cliffs  has  been  mei^ted  back  by  the  heat  reflected  from  the  rocks,  and  a 
deep  gulf  formed,  into  which  stones  falling  from  above  are  precipitated, 
and  injected,  as  it  were,  into  the  body  of  the  glaciers.  There  forbidding 
recesses,  black  with  accumulated  debris,  are  filled  and  buried  by  subse- 
quent snowfalls.  The  waste  from  the  cliffs  is  thus  at  the  start  sealed 
up  in  the  borders  of  the  flowing  ice  stream.  Much  of  the  morainal 
material,  when  it  begins  its  slow,  downward  journey  is  thus  inclosed  in 
the  snow  and  ice,  or  is  englacial.  It  becomes  superglacial  far  down  the 
glacier,  when  the  matrix  melts  and  the  foreign  bodies  contained  in  it  are 
concentrated  at  the  surface. 

The  ice  streams  advancing  down  lateral  valleys,  each  in  its  youth  a 
separate  and  independent  glacier,  unite  on  reaching  the  main  channel  and 
form  a  single  compound  stream.  The  various  branches  do  not  lose  their 
identity  and-  mingle  as  do  the  waters  of  confluent  rivers,  but  with  some 
change  of  form  flow  on  side  by  side.  This  is  plainly  shown  by  the 
behavior  of  the  marginal  moraines  on  the  adjacent  borders  of  two  glaciers 
after  they  unite.  The  two  lateral  streams  below  their  point  of  union 
form  a  single  medial  moraine  in  the  central  part  of  the  compound  stream. 
While  the  lateral  moraines  are  apparently  united,  they  still  retain  some- 


thin 

not 

side. 

amp 

mor; 

the 

man 


THE   LIFE    HISTORY   OF   A    GLACIER. 


195 


!.;5  ! 


thing  of  their  individuality.  The  material  of  which  they  are  composed  is 
not  at  firat  commingled,  but  continues  as  separate  streams,  flowing  side  by 
side.  If  one  glacier  is  fringed  with  fragments  of  white  quartzite,  for  ex- 
ample, and  its  neighbor  with  blocks  of  black  basalt,  the  compound  medial 
moraine  below  their  place  of  union  will  be  white  on  one  side  and  black  on 
the  other.  Such  a  division  of  a  medial  moraine  may  somet'  aes  be  noted 
many  miles  below  the  place  where  two  tributaries  unite.  On  highly  com- 
pound glaciei-s  the  medial  bands  sometimes  exhibit  a  score  or  more  of 
individual  threads. 

At  the  extremity  of  each  of  the  younger  glaciers  we  have  watched 
advancing  there  has  been  an  arch  in  the  ice,  from  beneath  which  a  stream 
of  muddy  water  flowed  out.  Each  glacier  is  the  source  of  a  stream,  and 
in  some  instances  discharges  a  swift,  roaring  torrent  having  the  volume 
of  a  river.  These  streams  pulsate  with  the  change  of  seasons.  Their 
volume  increases  in  summer  and  diminishes  in  winter.  Winter  and 
summer  they  are  heavily  charged  with  silt  and  mud,  while  the  streams 
with  which  they  unite,  lower  down  the  mountain,  where  there  are  no 
glaciers,  are  clear  except  after  rains.  Evidently  the  glaciera  are  wearing 
away  the  rocks  over  which  they  move,  and  the  streams  flowing  beneath 
them  are  carrying  away  the  finer  products  produced  by  the  ceaseless 
grinding.  The  young  glaciers  conceal  their  work,  and  we  must  wait  until 
they  grow  old  and  melt  away  before  we  can  discover  what  changes  are 
taking  place  in  the  channels  through  which  they  flow. 

Our  glacier  now  receiving  the  tribute  of  many  lateral  ice  streams  has 
passed  from  the  youthful  stage  to  maturity.  It  fills  the  valley  at  our  feet 
from  side  to  side,  and  is  prolonged  for  many  miles  below  the  shining  snow 
fields  from  beneath  which  we  watched  it  emerge.  The  vast  river  of  ice 
has  a  depth  of  a  thousand  feet  or  more  and  a  breadth  of  perhaps  one,  two, 
or  three  miles.  Its  width  is  less  than  the  united  breadth  of  its  many 
branches.  Its  great  thickness  is  due  to  the  lateral  compression  of  the 
tributaries  that  have  contributed  to  its  growth. 

The  distinction  is  well  marked  between  the  clear  white  n6\6  where  the 
surface  is  renewed  each  year  by  fresh  falls  oi  snow,  and  the  black  and 
dirt-staiued  ice  of  the  glacier  proper,  where  waste  exceeds  supply  and 
previously  englacial  material  is  being  concentrated  at  the  surface.  The 
glacier  proper,  as  well  as  the  n6v6,  is  snow-covered  each  winter  and  the 
details  of  its  surface  blotted  out,  but  with  the  return  of  summer  the  snow 
on  the  lower  portion  is  entirely  melted.  The  fringe  of  the  snow  mantle 
with  which  the  mountains  are  covered  is  withdrawn  higher  and  higher  as 


'■'il 


196 


GLACIERS  OF  NORTH  AMERICA. 


the  warm  season  advances,  until  in  late  summer  or  early  autumn,  just 
before  the  fii-st  storms  of  the  next  succeeding  winter  begin,  it  reaches  its 
maximum  elevation.  The  true  limit  between  the  surface  of  the  nev6  and 
of  the  glacier  proper  is  then  revealed.  The  snow  line  is  higher  on  rock 
surfaces  than  on  glaciers,  showing  that  the  dark  rocks  absorb  more  heat 
and  melt  the  snow  resting  on  them  more  thoroughly  than  does  the 
brilliant  ice.  In  onr  watch  of  centuries  we  note  that  the  snow  line 
experiences  many  fluctuations.  As  the  glaciers  increase  in  number  and 
in  size  and  their  ndves  broaden,  the  snow  line  descends  lower  and  lower, 
even  though  the  general  climatic  conditions  remain  sensibly  the  same. 
This  is  on  account  of  the  reaction  on  the  atmosphere  of  the  ice  bodies 
previously  formed.  The  snow  and  ice-covered  mountains  chill  the  winds 
blowing  over  tliem  more  than  formerly,  and  cause  heavier  precipitations. 
Each  storm  that  sweeps  over  the  white  peaks,  even  in  summer,  is  now 
accomi)anied  by  a  fall  of  snow.  Glaciers  thus  tend  to  change  their 
meteo    )logical  environment  in  such  a  way  as  to  favor  their  own  growth. 

The  trunk  glacier  in  the  valley  below  continues  to  advance  century 
after  century  and  increases  in  thickness,  particularly  towards  its  terminus. 
In  its  middle  and  upper  course,  and  especially  in  the  nevd  region,  the 
depth  of  the  frozen  flood  is  but  little  greater  than  during  the  earlier 
centuries  of  its  maturity. 

An  increase  in  the  thickness  of  a  glacier  which  flows  from  a  lofty 
mountain  while  due  mainly  to  a  decrease  in  the  gradient  of  the  valley  it 
occupies,  is  aided  also  by  an  increase  in  the  load  of  debris  it  carries.  Each 
of  these  changes  tends  to  increase  the  friction  of  flow,  but  as  the  advance  of 
ice  from  above  is  continuous,  the  lower  portion  of  the  glacier,  wheie  the 
current  is  more  sluggish,  must  increase  in  depth  or  in  breadth,  —  or  more 
precisely  in  area  of  cross  section,  —  in  order  to  enable  the  flood  to  pass. 

Another  agency  which  modifies  a  glacier's  life  also  increases  in  power 
as  the  glacier  advances,  namely,  the  heat  of  the  atmosphere.  The  lower 
a  glacier  descends  the  more  rapidly  is  it  melted.  The  gradient  of  its  sur- 
face is  thus  controlled  by  two  groups  of  antagonistic  agencies.  Decrease 
in  flow  causes  the  ice  to  increase  in  thickness,  while  melting  lowers  its 
surface.  Still  more  complexity  is  apparent  when  one  remembers  that  an 
increase  of  temperature  is  accompanied  by  an  increased  rate  of  flow. 
The  records  left  by  former  alpine  glaciers  in  Alaska  show  that  for 
many  miles  after  leaving  their  nev^s  they  increase  in  thickness,  but  as 
the  effect  of  the  increasing  temperature  of  the  lower  region  they  invaded 
was  felt,  they  gradually  decreased  in  thickness  and  receded. 


THE    LIFE   HISTORY   OF   A   GLACIER. 


197 


Returning  to  our  iniagiiuiry  glacier,  we  observe  that  in  its  onward 
march  it  cari-ies  the  mouths  of  lateral  valleys.  If  these  are  without  glaciers, 
or  if  the  ice  bodies  in  their  upper  courses  fail  to  reach  the  main  line  of 
drainage,  an  ice  dam  is  formed  in  the  main  valley,  the  drainage  in  the 
lateral  valleys  is  held  in  check,  and  lakes  appear.  The  accumulated  water 
may  escape  either  over  the  surface  of  the  ice  dam,  usually  at  its  junction 
with  the  rocky  side  of  the  valley  ;  but  more  frequently  the  water  disaj> 
peara  beneath  the  ice  and  finds  its  way  downward  through  sul>  or  englacial 
tunnels.  These  lakes  0:1  the  margin  of  the  glacier  are  subject  to  great 
fluctuations  on  account  of  changes  in  the  icy  channels  through  which  they 
discharge.  Not  infrequently  they  are  drained  suddenly,  and  floods  occur 
in  the  valley  below  the  end  of  the  glacier  that  confined  them.  The 
empty  basins  refill  when  the  outlet  becomes  again  closed  by  movements 
in  the  dam  of  ice.  Not  infrequently  their  surfaces  are  whitened  with 
floating  bergs,  from  which  boulders  are  scattered  over  the  bottom.  In 
spite  of  the  vicissitudes  that  beset  their  lives,  however,  we  learn  by  watch- 
ing their  basins  as  they  are  successively  filled  and  emptied,  tlutt  deposits  of 
sand  and  clay  are  formed  in  them,  and  under  favorable  conditions  may 
even  fill  the  depressions  up  to  the  level  of  the  wall  of  ice  which  in  part 
forms  their  boundaries.  Important  deposits  thus  originate,  and  may 
remain  as  a  part  of  the  geological  record  when  the  glacier  melts  and  the 
lakes  along  its  margins  are  drained. 

In  our  fancied  study  of  the  life  of  a  glacier  we  see  it  approach  a  por- 
tion of  the  valley  where  the  descent  is  rugged  and  broken.  The  yellow 
wallers  issuing  from  it  are  churned  into  foam  as  they  leap  from  ledge  to 
ledge.  On  reaching  the  place  of  steep  descent  the  glacier  becomes  greatly 
broken,  and  for  a  time  falls  in  detached  masses,  forming  a  veritable  ice 
cascade.  The  precipice  of  rock  is  heightened  by  a  wall  of  ice,  which  has 
a  serrate  crest  and  is  broken  into  towei-s  and  pinnacles,  separated  by  blue 
crevasses.  From  time  to  time  a  great  tower  falls  with  a  crash,  and  sends 
a  cloud  of  ice  fragments  rolling  down  the  valley.  The  steep  descent  soon 
becomes  blocked  with  fallen  fragments.  The  face  of  the  rocky  precipice 
is  concealed  from  view,  except  at  its  extremities,  where  it  joins  the  sides 
of  the  valley.  The  broken  and  pinnacled  ice  descending  the  precipice  is 
cemented  together  again  at  the  bottom,  and  the  glacier  flows  on,  with  but  few 
scars  caused  by  its  rough  passage  remaining.  At  the  ice  fall  the  descend- 
ing mass  impinges  with  great  force  on  the  rocks  at  the  bottom  of  the  slope, 
and  must  there  have  its  erosive  power  augmented.  Rock  basins  worn 
out  at  such  localities  will  be  seen  when  the  glacier  retreats.     The  ddbris 


198 


GLACIERS   OF   NORTH   AMERICA. 


carried  on  the  glacier  above  where  it  makes  its  steep  descent  is,  to  a  con- 
si  ;lerab!e  extent,  engulfed  in  crevasses,  but  a  portion  escapes  these  pitfalls 
and  still  darkens  the  surface  below  the  cascade.  A  part  of  the  stones 
that  Were  engulfed  soon  returns  to  the  surface,  by  reason  of  the  melting  of 
the  ice  ;  but  some  of  them  remain  for  a  long  time  in  an  englacial  or  sub- 
glacial  position.  At  each  sharp  descent  in  the  bed  of  the  glacier  an  ice 
cascade  appears.  When  the  grade  is  steep  but  not  precipitous,  the  ice 
is  greatly  broken  and  presents  the  appearance  of  a  rapid  rather  than  a 
cascade. 

The  surface  of  the  glacier  throughout  its  lower  course,  and  especially 
at  its  extremity,  is  dark  with  debris.  The  medial  moraines  so  prominent 
in  its  middle  course,  and  from  a  distance  appearing  like  winding  Mghways 
leading  from  the  land  of  flowers  to  the  land  of  snow,  become  less  well 
defined  and  less  definitely  separated  one  from  another.  The  reason  for  the 
flattening  and  spreading  that  the  moraines  suffer  is  not  far  to  seek.  Owing 
to  the  more  ra[)id  melting  of  the  clear  ice  the  portions  protected  by  debris 
are  left  in  relief.  The  medial  moraines  whc  e  best  defined  are  really  roof- 
like  ridges  of  ice  veneered  with  dirt  and  stones.  From  time  to  time  a 
rock  breaks  away  from  its  insecure  position  and  rolls  and  slides  down  the 
steep  slope  to  the  clear  ice  below,  thus  tending  to  widen  the  moraine- 
covered  tract.  On  gaining  a  new  position  the  fallen  block  again  protects 
the  ice  beneath  and  is  again  left  in  relief  by  the  melting  of  the  adjacent 
surface,  and  the  process  is  repeated.  The  falls  that  the  rock  masses  experi- 
ence—  and  the  larger  ones  receive  the  roughest  treatment  —  result  in 
many  fractures.  The  blocks  of  stone  are  thus  reduced  in  size  and  prepared 
for  future  usefulness  in  the  formation  of  soil.  Both  medial  and  lateral 
moraines  are  broadened  in  this  way,  and  in  time  lose  their  stream-like 
character,  and  the  general  surface  of  the  glacier  becomes  covered  with 
debris.  This  process  is  assisted  also  by  the  appearance  at  the  surface  of 
stones  previously  enclosed  in  the  ice,  but  not  associated  with  well-defined 
momines. 

The  accidents  that  happen  to  the  blocks  forming  surface  moraines,  on 
account  of  the  uneqvial  melting  of  the  glaciers,  are  repeated  on  a  smaller 
scale  by  individual  blocks  of  stone  large  enough  to  shelter  the  ice  on  which 
they  rest.  When  the  conditions  are  favorable,  such  blocks  of  stone  are 
raised  on  pedestals  and  form  glacier  tables.  These  growths  on  the 
glacier,  like  the  flowers  that  bloom  beside  it,  look  toward  the  sun  that  gave 
them  birth,  and  as  they  increase  in  height  incline  toward  his  mid-day 
position.      Finally,  they  slide  from   their  pedestals   and  the  process  is 


THE  LIFE   HISTORY   OP    A   GLACIER. 


199 


repeated.  Other  features  due  to  differential  melting  are  alao  present,  but 
belong  to  the  minor  tletails  of  the  siirfaue  where  waste  exceeds  supply,  and 
are  not  conspicuous  from  a  distance. 

The  glacier,  now  in  its  full  strength,  advances  from  the  extremity  of 
the  valley  that  sheltered  its  youth  and  guided  its  early  life,  and  invades 
the  piedmont  plain.  The  low  lands  are  densely  forested.  Majestic  spruce 
trees  and  aged  moss-covered  hemlocks  stand  in  thick,  serrate  ranks  across 
the  glacier's  path,  but  are  mowed  down  as  easily  as  the  grass  before  a 
scythe.  Crushed,  broken,  and  splintered,  the  trunks  are  piled  in  huge 
confused  heaps  and  overridden  and  buried  by  the  slow  but  resistless  march 
of  the  ice.  Where  the  waters  flowing  from  the  glacier  are  abundantly 
loaded  with  sand  and  gravel,  they  build  alluvial  deposits  about  its  margin. 
The  streams  in  their  passage  over  these  alluvial  cones  subdivide  and  send 
off  distributaries  into  the  forest  to  the  right  and  left,  and  the  trees  are 
surrounded  and  buried  by  sand  and  gravel  while  yet  standing.  A  fringe 
of  dead  trees,  in  part  denuded  of  their  branches,  marks  the  areas  wliere 
the  stream-borne  deposits  have  made  recent  conquests.  Under  these  con- 
ditions the  glacier  advances  over  the  buried  forests,  and  all  vestiges  of  its 
existence  are  blotted  out.  Centuries  later  the  still  erect  trunks  may  be 
revealed. 

The  rfile  that  a  glacier  plays  in  its  full  strength  when  it  invades  a  plain 
or  enters  a  broad  valley  may  be  said  to  depend  on  how  well  it  improved 
the  opportunities  of  its  youth.  If  the  debris  it  gathered  from  the  amj)hi- 
theatre  in  which  it  was  cradled  and  from  the  cliffs  that  sheltered  its  early 
course  is  sufficiently  abundant,  it  retains  its  stream-like  character  and 
builds  protecting  embankments  along  its  sides  as  it  advances.  If  the 
lateral  moraines  are  not  massive  in  comparison  with  the  volume  of  ice,  the 
glacier  expands  and  forms  a  semicircular  terminus  in  which  a  constantly 
increasing  area  of  surface  is  exposed  to  the  sun  and  rain.  Radial  cre- 
vasses appear  in  the  expanding  ice  foot  and  still  farther  assist  in  its 
destruction. 

A  ritical  point  of  the  life  of  a  glacier  has  now  been  reached.  Will  it 
have  strength  to  resist  the  increased  warmth  of  the  region  it  has  invaded 
and  continue  to  advance,  or  must  it  halt  at  an  intangible  boundary,  where 
the  annual  r.  elting  balances  the  flow  of  ice  from  higher  regions  ? 

In  our  fancied  watch  we  will  assume  that  the  glacier  is  not  only  unable 
to  advance  against  the  invisible  enemies  that  beset  its  progress,  but  that 
a  climatic  cycle  favorable  to  glacial  growth  has  passed  its  maximum  and 
begun  to  swing  in  the  opposite  direction.     Some  distant  cause,  possibly 


Ilk 


'iij 


200 


OLACIEUS    OF    NOUTII    AMEUICA. 


tlu)  uplieaval  of  a  iMirrier  in  the  oeeiiri,  or  the  slow  j^rowth  of  a  coral  reef, 
hm  deflected  an  ocean  current  that  formerly  bithed  the  a<ljacent  coast,  and 
the  winds  fail  to  hring  as  much  moisture  to  the  mountains  lus  formerly. 
Perhaps  the  relation  of  the  earth  to  the  sun  is  undergoing  a  secular 
change,  and  the  mean  annual  temperature,  and  the  relations  of  the  seasons 
are  so  modified  tiiat  for  thousands  of  yeara  conditions  unfavorable  to  the 
existence  of  perennial  snow  will  gradually  8Ui)plant  and  crowd  out  the 
favorable  conditions.  Prolmbly  a  combination  of  these  and  other  changes 
equally  gradual  in  their  effects  are  at  work  in  modifying  the  size  and 
shape  of  the  spheroid  of  32°,  and  the  snow  line  is  rising  at  the  rate  of  a 
few  feet  in  a  century. 

The  terminus  of  the  glacier  seemingly  remains  stationary  for  a  time, 
but  in  reality  is  seldom  at  the  same  line  for  many  successive  yeara.  Minor 
climatic  changes  experienced  scores  of  yeai-s,  or  perhaps  even  centuries 
previously,  at  the  fountains  from  which  it  flows,  are  transmitted  like 
pulsations  through  its  length,  and  its  extremity  advances  or  retreats  a  few 
feet  in  a  year  or  in  a  score  of  years.  Again,  climatic  changes  may  promote 
or  retard  melting  in  the  glacier  proper,  and  lead  to  less  sluggish  responses 
in  the  position  of  its  terminus.  Halts,  advances,  and  retreats  may  also  be 
caused  by  the  concentration  of  debris  in  its  wasting  extremity. 

The  glacier  has  now  passed  its  period  of  strength,  and  many  changes 
in  its  appearance  and  in  its  behavior  become  apparent.  The  flow  of  even 
the  most  rapid  threads  of  the  current  in  the  central  part  of  the  stream  is 
no  longer  sufficient  to  renew  the  surface  each  year  at  its  extremity.  The 
terminus  instead  of  advancing  is  now  slowly  retreating.  Melting  from 
the  surface  of  the  glacier  proper  is  in  .  ^ess  of  the  supply  of  ice  from 
higher  regions,  and  a  general  shrinking  and  lowering  of  the  surface  is  in 
progress.  The  stones  and  dirt  previously  held  in  the  ice  become  more 
rapidly  concentrated  at  the  surface.  Clear  ice,  especially  in  the  lower 
portions  of  the  glacier  proper,  is  no  longer  visible  except  in  crevasses. 
Vegetation  begins  to  take  root  on  the  previously  desolate  fields  of  debris. 
A  fringe  of  flowers  and  ferns  soon  margins  the  stagnant  portions,  and 
transforms  them  during  the  summer  season  into  luxuriant  gardens.  The 
forest,  previously  swept  away  as  a  thing  too  insignificant  to  be  worthy  the 
attention  of  the  legions  of  the  ice  king,  re-advances  year  by  year,  and  in 
time  flourishes  on  the  moraines  resting  on  the  ice  under  which  relics  of 
their  ancestors  lie  buried.  Animals  wander  through  the  forest  where 
moss  and  thick  undergrowths  conceal  pitfalls  in  the  ice  beneath,  and  are 
entrapped.     Man,  unattentive  to  the  wonders  about  him,  may  tread  the 


THE   LIFE   HI8TOUY   OF   A   OLACIEU. 


•201 


silent  aisles  of  the  forest  without  knowing  that  a  dead  glacier  lies  buried 
l»eneath  the  cari)et  of  vegetation  on  which  he  trea«ls.  As  the  ice  slowly 
melts  from  l)eneath  the  forest-covered  moraine,  openings  are  formed,  and 
lakelets  surrounded  with  rank  vegetation  give  variety  to  the  scene.  As 
these  pools  enlarge,  the  soil  and  lM)ulders  on  their  hanks  ar(>  undermined, 
and  uprooted  shrubs  and  trees  fall  into  them.  These  relics  of  the  forest, 
and  the  peaty  soi'i  formed  where  the  dei)rcssions  are  partially  drained, 
become  buried  in  morainal  debris.  Many  a  puzzling  record  is  thus 
preserved  which  will  lead  students  astray  in  future  centuries. 

The  forest-covered  border  of  the  fringing  moraine  is  separated  from 
the  clear  ice  by  broad  areas  of  desolation,  on  which  scarcely  a  lichen  has 
taken  root.  On  these  monotonous  wastes  striking  changes  are  likewise 
in  progress.  Scores  and  perhaps  hundreds  of  lakes  are  formed,  similar  to 
those  in  the  forest-covered  moraine,  but  producing  more  apparent  results, 
since  the  debris  about  them  id  not  covered  with  a  mask  of  vegetation. 
As  these  walls  of  ice  alx)ut  the  lakelets  melt,  tiie  stones  and  dirt  on  the 
adjacent  surface  are  precipitated  into  them,  and  accumulate  deeply  over 
their  bottom.  When  the  general  surface  is  lowered  by  melting,  these 
deeply  filled  holes  are  transformed  into  prominences  thickly  covered  with 
earth  and  stones.  The  irregular  piles  assume  a  jjyramidal  form,  because 
of  the  displacement  and  sliding  down  of  the  rock  masses  on  their  borders. 
In  time  the  sites  of  the  basins  of  muddy  water  are  marked  l)y  huge  pyra- 
mids of  ice,  a  hundred  feet  or  more  in  height  but  concealed  from  sight  by 
a  veneer  of  stones.  From  our  observing  station,  scores  and  hundreds 
of  those  monuments  are  in  view.  Between  them  are  many  lakelets  not 
yet  filled,  and  others  that  have  been  drained  of  their  water  but  are  yet 
unsightly  de])ressions  in  which  the  stones  are  covered  with  slimy  mud. 

While  the  changes  noted  near  the  extremity  of  the  glacier  have  been 
in  progress,  other  signs  of  old  age  have  appeared  far  up  its  couree.  The 
ice  no  longer  fills  the  valley  as  deeply  as  befoie,  but  an  api)arent  settling 
of  its  surface  has  occurred.  The  mountain  slopes  rising  above  its  borders 
are  either  bare  or  sheathed  with  debris  left  stranded  as  the  current  sub- 
sided. The  height  of  the  ice  during  its  maximum  is  marked  on  each 
side  of  the  valley  by  an  abandoned  lateral  moraine.  This  ridge  is 
frequently  a  well-defined  teixace  or  shelf  on  the  steep  slope.  The 
border  overlooking  the  valley  is  higher  than  the  margin  adjacent  to  the 
mountain,  and  forms  a  ridge  composed  of  boulders  and  stones  of  many 
sizes  and  shapes.  Between  the  ridge  and  the  upward  slope  of  the  moun- 
tain, there  is  frequently  a  level-floored  space,  formed  of  sand  and  gravel 


202 


GLACIEKS   OP   NORTH   AMFRICA. 


swept  by  torrents  from  the  region  above.  Streams  descending  lateral 
gulliei  re  deflected  by  tlie  outer  ridge,  and,  should  the  general  grade  of 
the  vali    '  be  sufficiently  gentle,  may  form  lakelets  and  swamps. 

The  slope  of  the  abandoned  lateral  moraines,  or  their  gradient,  is 
plainly  less  than  the  gradient  of  the  surface  of  the  ice  still  remaining  in 
the  bottom  of  the  trough.  Far  down  the  valley,  near  where  it  opens  out 
on  the  piedmont  plain,  their  elevation  may  be  a  thousand  feet  above  the 
surface  to  the  stagnant  ice,  but  as  one  traces  them  up  stream  this  interval 
becomes  less  and  less,  until  in  proximity  to  the  lower  border  of  the  mantle 
of  perennial  ynow,  the  two  coincide.  This  is  the  reverae  of  the  process 
noted  during  the  au  vance  of  the  glacier,  when  the  strong  current  caused 
the  ice  to  thicken  most  rapidly  at  a  distance  below  the  source  of  supply, 
and  shows  tJiat  Summer  is  invading  the  realm  of  Winter. 

The  highest  lateral  moraine  left  stranded  as  the  ice  melts,  marks  the 
limit  lietween  the  rugged  and  angular  crags  that  have  been  long  exposed 
to  the  action  of  frost  and  rain,  and  the  surfaces  which  have  been  worn 
and  rounded  by  flowing  ice.  Above,  the  lines  in  the  sculpturing  are 
more  or  less  vevkcal,  in  conformity  with  the  direction  of  flow  of  the 
streams  and  rilU  that  made  them  ;  below,  the  most  pronounced  elements 
in  the  relief  trend  in  the  direction  of  the  major  axis  of  the  valley,  and 
appear  to  be  approximately  horizontal. 

Most  interesting  of  all  the  records  on  the  sides  of  the  valley  left 
exposed  by  the  shrinking  of  the  ice,  but  scarcely  discernible  from  a  distance, 
are  lines  and  grooves  on  the  ice-worn  surfaces.  When  the  rocks  are 
hard  and  fine-grained,  their  pol'shed  surfaces  glitter  in  the  sunlight  like 
burnished  granite  fresh  from  the  builder's  hand.  A  near  view  will 
generally  show,  however,  that  the  tools  that  did  the  polishing  were  not 
carefully  selected.  The  glaciated  surfaces  are  covered  by  scorings  of 
varying  character,  from  light,  delicate  lines,  such  as  might  be  traced 
with  a  diamond's  point,  up  to  deep  grooves  and  heavy  irregular  gouges, 
geemingly  made  by  huge  boulders  of  hard  rock  forced  along  under  heavy 
pressure.  The  more  even  lines,  especially,  are  in  parallel  series  and  trend 
in  the  direction  of  ice  movement.  Similar  markings  are  also  to  be  found 
at  the  extremity  of  the  glacier  wherever  its  retreat  has  exposed  the  hard 
rocks  over  v  hich  it  passed.  A  close  inspection  will  reveal  many  localities 
where  the  glacial  ice  charged  with  sand  and  stones  rests  directly  in  con- 
tact with  polished  and  striated  surfaces.  The  manner  in  which  the 
graving  tools  that  made  the  inscriptions  are  held  in  the  icy  matrix  is  thus 
revealed. 


THE   LIFE   HISTORY    OF   A   GLACIER. 


203 


As  we  watch  the  slowly  receding  extremity  of  the  glacier,  we  note 
that  its  rate  of  retreat  is  not  uniform.  At  times  it  remains  practically 
stationary  for  many  yeai-s,  and  the  debris  carried  forward  on  its  surface 
is  concentrated  in  its  extremity.  When  the  glacier  again  retreats,  an 
irregular  accumulation  of  boulder,  stone,  sand,  and  earth,  indiscriminately 
commingled,  is  left  as  an  embankment  across  the  valley.  The  crest  of 
the  ridge  forms  a  curve  concave  up  stream,  and  is  apt  to  have  its  more 
gentle  slope  on  the  side  facing  the  shrunken  glacier.  Several'  such 
crescent-shaped  piles  may  be  left  as  the  glacier  slowly  retires.  Many  of 
these  abandoned  terminal  moraines  form  dams  above  which  the  drainage 
from  the  glacier  and  from  adjacent  slopes  is  retarded,  and  lakes  are 
formed.  These  lakes,  like  those  originating  along  the  sides  of  the  glacier 
during  its  advance,  are  short-lived.  They  rise  rapidly  as  the  ice  with- 
draws, and  in  fact  are  flooded  and  begin  to  overflow  long  before  the 
retreat  of  the  ice  has  allowed  them  to  fully  expand.  While  yet  sni.dl, 
they  are  turbid  with  glacial  silt  and  have  a  peculiar  yellowish  green  color. 
When  they  reach  a  large  size,  their  waters  are  more  or  less  perfectly 
clarified,  and  may  appear  as  a  plain  of  blue  in  which  the  majestic  moun- 
tains are  mirrored.  Where  glacial  streams  enter,  there  is  always  a  fringe 
of  yellow  shading  off  through  innumerable  tints  to  the  clear  blue  beyond 
and  showing  that  abundant  sediments  are  there  being  deposited.  Unfor- 
tunately, as  it  would  seem,  various  agencies  conspire  to  deface  and  to 
remove  these  pleasing  results  of  glacial  agencies.  The  lake  basins  are 
rapidly  filled  with  sediment,  and  the  overflowing  water  cuts  deep  channels 
through  the  unconsolidated  material  that  holds  them  in  check.  For  these 
reasons,  they  pass  rapidly  through  their  predestined  changes,  and  finally 
are  completely  drained  and  their  bottoms  transformed  into  smiling 
meadows.  Dark  evergreen  forests  border  the  even  meadows  of  waving 
grass,  and  flowera  beautify  their  surfaces.  The  now  sluggish  streams 
meander  in  many  graceful  curves  between  banks  that  are  outlined  by 
the  pink  of  budding  willows  in  spring  and  with  the  gold  of  aspen  leaves 
in  autumn.  Deer  and  other  inhabitants  of  the  region  find  there  a 
sheltered  retreat.  The  once  frozen  solitude  is  transformed  into  a  park, 
more  beautiful  and  richer  in  delicate  charms  than  man  has  yet  designed. 
The  plowshare  of  ice  that  descended  from  the  mountains  broke  the  flinty 
rocks  and  prepared  the  land  for  the  harvest. 

While  watching  the  transformation  from  stern  winter  to  smiling 
summer  in  the  lower  valley,  the  extremity  of  the  glacier  has  receded 
above  that  portion  of  its  bed  where  great  crevasses  and  ice  cascades  broke 


A 


204 


GLACIERS   OF   NORTH   AMERICA. 


its  surface  during  its  descent.  At  the  base  of  these  steep  slopes,  now 
worn  and  rounded,  other  lakes  are  born.  Their  cradles  are  hollows  in  the 
solid  rock.  No  moraine  piles  hold  the  water  in  check,  but  the  rims  of 
their  basins  are  polished  and  striated  ledges.  Could  we  see  their  bottom, 
we  would  find  that  they,  also,  are  smoothed  and  rounded.  As  the  ice 
withdraws  from  the  higher  portions  of  its  bed  the  number  of  rock-enclosed 
tarns  increases,  and  fresh  charms  are  added  to  the  diversity  and  beauty  of 
the  region.  In  neighboring  valleys  and  adjacent  slopes  where  the  rocks 
are  essentially  the  same  but  have  not  been  subjected  to  glacial  action,  rock 
basins  are  absent.  Evidently  their  abundance  in  the  abandoned  beds  of 
the  retreating  glacier  is  the  result  of  the  abrasion  that  the  rocks  suffered 
from  the  ice  that  moved  over  them.  They  are  plentiful  where  the  descent 
is  precipitous,  and  absent  at  lower  levels,  where  the  grade  of  the  ice  stream 
was  gentle.  The  region  where  they  occur  is  notably  free  from  moraines 
and  other  glacial  deposits  ;  lower  down  the  valley  where  they  are  absent 
there  are  heavy  accumulations  of  debris.  That  their  rarity  in  the  lower 
part  of  the  valley  is  not  due  to  the  masking  of  the  hard-rock  surfaces  by 
glacial  deposits  is  shown  by  their  absence  from  areas  where  such  deposits 
are  lacking.  The  regions  where  the  rock  basins  are  most  abundant  are 
regions  where  abrading  and  transporting  agencies  were  active  ;  the  lower 
portion  of  the  valley  where  they  do  not  occur  are  where  the  glacier  did 
least  work,  and  where  deposition  and  not  erosion  was  the  rule.  Where 
the  glacier  was  heavily  charged  with  debris  it  became  sluggish  and  did  but 
little  abrading.  In  many  instances  rock-basin  lakes  are  situated  at  the 
bottom  of  steep  inclines,  down  which  the  ice  descended  and  pressed  with 
great  force  on  the  rocks  where  there  is  an  abrupt  change  to  a  more  gentle 
grade.  The  rock-enclosed  lakes  are,  in  general,  longer-lived  than  those 
held  by  moraines,  but  in  time  they  too  become  filled  with  sediment  and 
are  transformed  into  brilliant  gardens  of  alpine  flowers. 

Had  our  glacier  advanced  boldly  into  the  piedmont  plain,  possibly 
another  variety  of  rock  basin  would  have  been  excavated,  but  in  the  fan- 
cied instances  before  us  it  is  not  practicable  to  include  a  complete  analysis 
of  glacial  action. 

The  last  stages  in  the  decline  and  death  of  a  glacier  are  slow  and 
frequently  much  prolonged.  The  blue  ice  visible  below  the  margin  of  the 
white  n6v6  contracts  more  and  more,  until  during  certain  seasons,  or  for  a 
series  of  yeara,  it  is  completely  concealed  by  a  covering  of  snow.  Fluctua- 
tion still  occurs,  however,  and  during  years,  or  a  succession  of  years,  when 
the  winter  snows  are  light,  or  summer  melting  accelerated,  the  glacier 


THE   LIFE   HISTORY    OF   A   GLACIER. 


205 


proper  may  be  seen  for  a  short  time  in  late  summer  or  early  autumn.  In 
its  old  age  the  glacier  reaches  a  second  childhood  in  which  the  character- 
istics of  its  early  years  again  appear.  So  complete  is  this  similarity  in 
many  instances  that  it  is  difficult,  if  not  impossible,  for  one  to  decide 
whether  a  miniature  glacier  sheltered  in  the  encircling  arms  of  a  mountain 
crest,  is  the  beginning  of  a  new  ice  extension  or  the  remnant  of  a  glacial 
epoch  that  has  nearly  passed  away.  The  depth  and  character  of  the 
amphitheatre  in  which  the  snow  and  ice  lie,  and  the  shape  and  sculptur- 
ing of  the  valley  leading  from  it,  may  furnish  proof  of  a  former  period  of 
intense  glaciation.  But  whether  in  many  instances  the  glacier  that  did 
the  work  was  completely  melted  and  a  new  period  of  ice  extension  initi- 
ated, or  vrhether  a  remnant  of  the  dying  glacier  still  remains,  I  know  of 
no  test  by  which  to  decide. 

Throughout  the  growth  and  decadence  of  the  glacier  we  have  been 
watching,  it  has  been  apparent  that  even  the  grandest  results  have  been 
attained  by  slow,  and  as  they  ordinarily  appear  to  us,  imperceptible 
changes.  More  than  this,  the  climatic  variations  made  manifest  by  the 
behavior  of  a  glacier  do  not  go  on  continuously  in  one  direction  for  long 
periods,  but  are  accomplished  by  irregular  pulsations.  There  have  been 
great  cycles  favoring  growth  or  decline,  and  within  these  there  have  been 
minor  periods  during  which  the  changes  in  progress  were  retarded  and 
even  reversed  ;  but  the  resultant  of  several  minor  periods  coincided  with 
the  general  change  in  progress. 

It  is  safe  to  gay  that  the  main  features  in  the  life  histories  of  even  the 
greatest  piedmont  and  continental  glaciers  are  similar  to  those  presented 
by  a  single  ice  stream  of  the  alpine  type.  Even  the  coming  ar^d  going  of 
glacial  periods  are  so  far  as  one  can  judge  in  obedience  to  similar  laws. 
The  records  left  by  Pleistot  ne  ice  sheets  show  that  they  underwent  many 
fluctuations,  s*  .me  of  which  w  ere  so  pronounced  that  they  are  usually  con- 
sidered as  indej  ident  periods.  One  of  these  pulsations  embraced  a  far 
greater  lapse  of  me  than  the  entire  life  history  of  a  glacier  such  as  has 
just  been  traced. 

A  wonderful  \ista  is  unfolded  when  one  attempts  to  include  in  a 
single  mental  picture  the  transformations  that  accompany  a  climatic  revo- 
lution so  vast  that  a  continent  became  buried  beneath  thousands  of  feet  of 
ice,  and  on  retiring  left  a  soil  in  which  the  most  advanced  civilization 
known  to  history  took  root.  Surely  such  a  theme  is  worthy  of  being 
interpreted  in  a  great  poem,  beside  which  the  vision  of  a  Dante  or  a  Milton 
would  be  lacking  in  interest. 


203 


GLACIERS   OF   NORTH   AMERICA. 


Concluding  Note. 

In  preceding  chapters  I  have  attempted  to  present  a  review  of  what 
is  known  concerning  the  existing  glaciers  of  North  America,  and  have 
indicated  in  many  instances  where  more  detailed  information  in  refer- 
ence to  special  regions  and  to  individual  glaciers  may  he  found.  I  have 
also  ventured  to  point  out  in  some  cases  the  direction  in  which  new 
explorations  in  this  fascinating  field  can  be  most  profitably  undertaken. 
In  the  chapter  just  concluded  an  attempt  was  made  to  present  in  one  view 
an  outline  of  the  life  history  of  a  single  alpine  glacier.  A  continuation 
of  the  studies  here  begun  would  naturally  lead  to  a  review  of  the  records 
left  by  extinct  glaciers,  since  in  this,  as  in  many  other  departments  of 
geology  and  physiography,  "the  present  is  the  key  to  the  past";  but  as 
our  fireside  journey  over  mountains  and  across  ice  fields  has  been  long  and 
arduous,  I  will,  for  the  present,  part  company  with  the  reader  here. 

For  the  benefit  of  the  student  who  may  desire  to  continue  the  course 
of  reading  to  which  this  book  is  intended  as  an  introduction,  I  would 
suggest  the  numerous  memoirs  on  surface  geology  contained  in  the  annual 
reports  of  the  United  States  Geological  Survey  and  in  The  Journal  of 
Geology,  published  at  the  University  of  Chicago. 


IIS^DEX. 


Abrasion  of  glaciers,  described,  18-21. 

Advance  glacier,  136. 

Advance  of  Malaspina  glacier,  127. 

Agassiz,  L.,  Views  of,  on  glacial  motion,  144. 

Agassiz  glacier,  1 10. 

Alaska,  Ketreat  of  glaciers  in,  150-150. 

Glaciers  of,  74-129. 

Alaskan  peninsula.  Glaciers  of,  108,  109. 
Aleutian  islands.  Glaciers  of,  108,  109. 
Allen,  H.  T.,  Journey  of,  in  Alaska,  105. 
Alluvial  cones,  Malaspina  glacier,  125,  126. 
Alpine  glacier.  Term  defined,  2. 

glaciers  of  Alaska,  96-104. 

Auk  glacier,  104. 

Baker,  Mt.,  Glaciers  of,  69,  70. 

Baldwin,  S.  P.,  Observations  on  Muir  glacier 

by,  82. 
Belcher,  Sir  Edward,  Voyage  of,  75. 
Bell,  W.  H.,  Cited  on  glaciers  of  Stikine 

river,  75. 
Bergschrund,  Description  of,  9. 
Bering  glaciers,  Alaska,  Mention  of,  96. 
Biake,  W.  P.,  Cited  on  glaciers  of  Stikine 

river,  75. 
Bowdoin  glacier,  Eate  of  fiow  of,  144. 
Brewer,   H.    W.,   Cited   on   Sierra  Nevada 

glaciers,  43. 
Brainard,  O.  L.,  Explorations  by,  132. 
British  Columbia,  Retreat  of  glaciers  in,  149. 
Bulam  glacier,  01. 

California,  Evidence  of  retreat  of  glaciers 

in,  148. 
Geological  survey  of,  in  the  High  Sierra, 

61,  52. 

Northern,  Glaciers  of,  66-62. 

Canada,  Glaciers  of,  71-73. 
Cantwell,  J.  C  ,  Explorations  by,  128. 
Chaney,   L.  W.,  Jr.,  Cited  on  glaciers  in 

Montana,  33. 


Chapin,  F.  H.,  Cited  on  glaciers  in  Colorado, 

33. 
Chaix  hills,  Alaska,  Lakes  near,  118-121. 
Cirques,  Mention  of,  10. 
Chamberlin,  T.   C,  Cited  on  the  cause  of 

glacial  motion,  183-185. 

Cited  on  roi  k  scorings,  21. 

Explanation  of  ^iacial  motion  by,  170- 

172. 

Observations  by,  132. 

Observations  by,  in  Greenland,  142. 

Reference  to  writings  of,  135. 

"Chinese  Wall,"  Grinnell  land,  132. 
Climatic  changes  shown  by  glaciei-s,  140-159. 
Colman,  E.  T. ,  Cited  on  glaciers  of  Mt.  Baker, 

69,  70. 
Continental  glacier.  Term  defined,  2. 
Cordilleran  region.  Briefly  described,  32. 
Cowlitz  glacier,  64. 
Crevasses,  Formation  of,  7-10. 

General  description  of,  7,  8. 

in  the  glaciers  of  the  High  Sierra,  42. 

Croll,  J.,  Cited  on  the  flow  of  glaciers,  179-181. 

Reference  to  works  of,  163. 

References  to  the  writings  of,  181. 

Cushing,  H-  P.,  References  to  writings  of,  87. 

Dall,  W.  H.,  Fossils  identified  by,  127. 

Dana,  Mt.,  Height  of,  and  glacier  on,  39,  40. 

Davidson,  George,  Cited  in  reference  to  gla- 
ciers of  Mt.  Rainier,  62. 

Glacier  named  in  honor  of,  102-104. 

Davidson  glacier,  Alaska,  102-104. 

Mention  of,  3. 

Davis,  W.  M.,  Reference  to  writings  of,  103. 

Dawson,  G.  M. ,  Cited  on  retreat  of  glaciers, 
149. 

Cited  on  Vancouver  system,  32. 

Debris,  Influence  of,  on  movements  of  glaciers, 
25-28,  158,  188. 

Deeley,  R.  M.,  Cited  on  grain  of  ice,  175. 


208 


INDEX. 


Deeley,  R.  M.,  Reference  to  writings  of,  185. 

"  Devil's  slides,"  50. 

"  DeSaussure's  Theory,"  Brief  statement  of, 

163. 
Disrupted  gouges.  Mention  of,  21. 
Dilatation  hypothesis  of  glacial  motion,  164. 
Diller,  J.  S.,  Cited  on  glaciers  of  Cascade 

region,  70. 
Cited  on  glaciers  of  Mt.  Shasta,  56,  60, 

61,  62. 
Dirt  bands  on  Sierra  Nevada  glaciers,  43. 
Disenchantment  bay,  Alaska,  Glaciers  of, 

02-96. 

Retreat  of  glaciers  of,  151-163. 

Drainage  of  Malaspina  glacier,  121-123. 
Driftless  area,  Alaska,  107. 

Greenland,  134,  145. 

Drumlins,  described,  24-28. 
Dundas  bay,  Alaska,  Glaciers  of,  91. 
Dust  on  glaciers.  Mention  of,  6. 

Eagle  glacier,  104. 

Eclectic  hypothesis  of  glacial  motion,  186-189. 
Emmons,  S.  F.,  Cited  on  glaciers  of  Mt. 
Rainier,  63-66. 

Fletcher,  G.,  Cited  on  grain  of  ice,  175. 
Fish  on  Malaspina  glacier,  14. 
Forest  beneath  Muir  glacier,  86,  87. 
beneath  gravel,  Malaspina  glacier,  125- 

126. 

on  moraines  of  Malaapina  glacier,  117. 

Forbes,  J.  D.,  Cited  on  glaciaf  motion,  165, 

166. 
Fossils  from  margin  of  Malaspina  glacier, 

127. 

Gardner,  T.  C,  Cited  on  ice  blades,  51. 
Geikie,  J.,  Reference  to  writings  of,  135. 
Geological  Survey  of  California,  Work  of,  in 

the  High  Sierra,  51,  62. 
Gilbert,  G.  K.,  Visit  of,  to  Mt.  Lyell,  38,  48. 
Glacial  and  ocean  records,  120. 
Glacier  bay,  Alaska,  Glaciers  on  west  side  of, 

91,  92. 

Retreat  of  glaciers  of,  150,  151. 

Glacier  garden,  Switzerland,  14. 
Glacier  tables,  Account  of,  11. 

on  Parker  Creek  glacier,  California,  44. 

Glave,  E.  J.,  Glaciers  seen  by,  in  Alaska,  105. 
Grain  of  glacial  ice,  6,  103,  188. 
Granular  change  in  glaciers,  183. 


Greely,  A.  W.,  Explorations  by,  131,  1.32. 
Green,  W.  S.,  Cited  on  the  glaciers  of  Selkirk 

mountains,  Canada,  71,  72. 
Greenland,  Advance  and  retreat  of  glaciers 

of,  155,  156. 

Glaciers  of,  133-159. 

region.  Glaciers  of,  35,  36,  131-159. 

Groton,  Mafis.,  Drumlins  near,  24,  25. 
Guyot  glacier,  101,  110. 

Ilaenke  island,  Alaska,  View  from,  92,  93. 
Hague,  Arnold,  Cited  on  the  glaciers  of  Mt, 

Hood,  68,  69. 
Hayes,  C.  W.,  Cited  on  glaciers  of  Alaska, 

76,  105,  106. 
C'ted  on  retreat  of  Alaskan  glaciers, 

U3-159. 

Journey  of,  in  Alaska,  105. 

Healy,  M.  A.,  Reference  to  writings  of,  128. 
Heim,  A.,  Cited  on  grain  of  ice,  175. 
Henrietta  Nesmith  glacier,  Grinnell  land,  132. 
High  Sierra,  California,  Description  of,  37, 38. 

General  characters  of,  33,  34. 

Hood,  Mt.,  Glaciers  of,  67-69.  • 
Hopkins,  W.,  Investigations  by,  163,  164. 
Hotlum  glacier,  61. 
Hubbard  glacier,  Alaska,  Brief  account  of, 

92-94. 
Humboldt  glacier,  Greenland,  Brief  account 

of,  134,  135. 
Hutli  glacier,  Alaska,  Reference  to,  78. 
Hypotheses  of  glacial  motion,  160-189. 

Icebergs,  Origin  of,  Discussed,  83-86. 
Ice  pyramids  on  Mt.  Lyell  glacier,  46,  46. 
Ice  tongues  of  Sierra  Nevada  glaciers,  47,  48. 
Icy  cape,  Alaska,  Brief  account  of,  96,  96. 
Icy  strait.  Former  extent  of  ice  in,  90. 
Illecellewaet  glacier.  Brief  description  of,  72. 

Johnson,  W.  D.,  Observations  of,  in  Califor- 
nia, 38,  39. 
Juneau  glacier,  104. 

Kane,  Cited  on  Humboldt  glacier,  135,  1.36. 
Kautz,  A.  v.,  Ascent  of  Mt.  Rainier  by,  62. 
Kidd,  D.  A.,  Experiments  by,  167. 
King,  C,  Cited,  52. 

Cited  on  glaciers  of  Mt.  Shasta,  55-58. 

Klocke  Fr.,  Observations  by,  162.  ' 
Klutlan  glacier,  106. 
Rr cession  of,  163. 


INDEX. 


209 


Koch,  K.  H.,  Observations  by,  162. 
Konvvakiton  glacier,  GO. 
Kotzebue  sound.  Ice  cliffs  of,  128. 

Lake  Cast^iai,  Alaska,  Brief  account  of,  121. 
Likes,  Marginal,  of  Malaspina  glacier,  118- 

121. 

on  Malaspina  glacier,  115,  11(5. 

Le  Conte,  J.,  Cited  on  "  ice  blades  "  of  Sierra 

Nevada  glaciers,  42. 
Explorations  by,  in  the  High  Sierra, 

,00,  61. 
Lemon  Creek  glacier,  104. 
Lenticular  hills,  see  Drumlins. 
Libbey ,  Jr. ,  W. ,  Cited  on  Alaskan  glaciers,  76. 
Life  history  of  a  glacier,  189-205. 
Lockwood,  Cited  on  glaciers  of  N.  Greenland, 

138. 

Explorations  by,  132. 

Loess,  Mention  of,  16. 

Logan,  Mt.,  Height  of,  74. 

Lyell,  Mt.,  California,  Glaciers  on,  40,  41. 

Height  of,  40. 

Lynn  canal,  Alaska,  Glaciers  of,  101-104. 
lletreat  of  glaciers  on,  150. 

Malaspina  glacier.  Description  of,  109-127. 

Mention  of,  3. 

Mention  of  tunnels  in,  16. 

Moraines  on,  12. 

Recession  of,  151,  162. 

Malaspina's  expedition,  Reference  to,  92. 
Mammillary  hills,  see  Drumlins. 
Marginal  lakes  of  Malaspina  glacier,  118-121. 
Mathews,  W.,  Views  on  glacial  motion,  169. 
McConnel,  J.  C,  Experiments  by,  167. 
McConnel,  R.  G.,  Cited  on  retreat  of  glaciers, 

149. 
McClure,  Mt.,  California,  Height  of,  40. 
Mexico,  Height  of  peaks  in,  33. 
Mer  de  Glace,  A  type  of  alpine  glaciers,  1. 
Mer  de  Glace  Agassiz,  Grinnell  land,  132. 
Miles  glacier.  Recession  of,  153. 
Molecular  motion  in  glaciers,  179-183. 
Moraines,  Characteristics  of,  12. 

decribed,  22-24. 

Ideal  sketch  of,  7. 

of  Malaspina  glacier,  113-118. 

of  Sierra  Nevada  glaciers,  46. 

Varieties  of,  6,  7. 

Moseley,  H.,  Cited  on  movements  of  glaciers, 

176. 


Moseley,  H.,  Experiments  by,  169. 
Movements  of  glaciers.  Explanations  of,  160- 

189. 
Mt.  Dana  glacier,  Description  of,  35-40. 
Mt.  Lyell  glacier.  Description  of,  40,  41. 
MUgge,  O.,  Experiments  by,  167,  168. 
Mulr,  John,  Cited  on  Alaskan  glaciers,  76. 

Cited  on  glaciers  of  Glacier  bay,  91. 

Discovery  of  Muir  glacier  by,  80. 

Explorations  of,   in  the  High   Sierra, 

49,  50. 
Muir  glacier,  Alaska,  Description  of,  80-91. 
Recent  recession  of,  160,  161. 

Nansen,  F. ,  Explorations  of  the  inland  ice  of 
Greenland,  140,  141. 

Reference  to  writings  of,  135. 

N^v^s,  Characteristics  of,  4,  6. 

of  glaciers  in  the  Sierra  Nevada,  Colo- 
ratio,  42. 

Newberry,  J.  S.,  Reference  to  observation  by, 
70. 

Nisqually  glacier,  Mt.  Rainier,  64. 

Nordenskiold,  Baron,  Explorations  by,  in 
Greenland,  139,  140. 

Norrls  glacier,  Alaska,  Reference  to,  78. 

North  America,  General  distribution  of  gla- 
ciers, 32-36. 

Nunatak,  Meaning  of  the  term,  133. 

Nunatak  glacier,  Alaska,  Brief  account  of, 
92-94. 

Nunataks  of  Greenland,  133. 

Oregon,  Evidence  of  retreat  of  glaciers  in, 

149. 
Osars,  described,  28,  29. 

of  Malaspina  glacier,  123-125. 

Osier  island,  Alaska,  View  from,  95. 

Parker  Creek  glacier,  California,  Description 

of,  41,  43,  44. 
Pacific  glacier,  Alaska,  91. 
Peary,  R.  E.,  Journeys  In  Greenland,  140. 

Cited  on  flow  of  Bowdoin  glacier,  144. 

Cited  on  glaciers  of  Greenland,  135. 

Explorations  by,  133,  135. 

Piedmont  glaciers.  Description  of,  109-127. 

Term  defined,  2. 

Plasticity  hypothesis  of  glacial  motion,  166. 
Pleistocene  glaciers  of  the  Sierra  Nevada, 

62-64. 
Pot-holes,  Origin  of,  14. 


210 


INDEX. 


Rainier,  Mt.,  Washington,  Glaciers  of,  62-67. 

Recent  ascents  of,  67. 

Recession  of  Muir  glacier,  1)0,  ttl. 

Red  snow  of  Sierra  Nevada  glaciers,  48. 

Regelation  hypothesis  of  glacial  flow,  172-176. 

Reid,  II.  F.,  Cited  on  Alaskan  glaciers,  76. 

Cited  on  origin  of  icebergs,  85,  86. 

- —  Cited  on  variations  of  glaciers,  166. 

Observations  on  Muir  glacier  by,  81. 

References  to  writings  of,  87,  01. 

Rhone  glacier,  Mention  of,  3. 

Richter,  Cited  on  variations  of  glaciers,  153. 

"  Ribbon  structure "  in  Sierra  Nevada  gla- 
ciers, 42. 

Rink,  H.,  Reference  to  writings  of,  135. 

Russell,  I.  C,  Papers  on  Alaskan  glaciers 
by,  70. 

References  to  writings  of,  87. 

Russell  glacier,  Alaska,  106. 

Recession  of,  153. 

St.  Elias,  Mt.,  Height  of,  74. 
View  from,  97,  08. 


St.  Elias  region,  Alaska,  Retreat  of  glaciers 
of,  151,  152. 

Salisbury,  R.  1). ,  Visit  of,  to  Greenland,  145. 

Sand  cones.  Brief  account  of,  13, 

Origin  of,  13. 

Sand  plains,  described,  29. 

Schwatka,  F.,  Journey  of,  in  Alaska,  105. 

S-idiments  of  glaciers,  Definition  of  term,  28. 

Selkirk  mountains.  Glaciers  of,  71,  72. 

Selwyn,  A.  R.  C,  Cited  on  Vancouver  sys- 
tem, 32. 

Seton-Karr,  H.  W.,  Cited  on  glaciers  of 
Alaska,  76. 

Seward  glacier,  Alaska,  98-101. 

Shaler,  N.  S. ,  Reference  to  writmgs  of,  103. 

Sha.sta,  Mt.,  California,  Glaciers  of,  55-62. 

Sierra  Nevada,  California,  Description  of  gla- 
cierstof,  37-54. 

Sita-da-ka  glacier,  Alaska,  see  Muir  glacier. 

Sliding  hypothesis  of  glacial  motion,  103. 

Smith,  E.  C,  Ascent  of  Mt.  Rainier  by,  67. 

Snow-line,  Definition  of,  5. 

Striae,  Direction  of,  20. 

Striated  surfaces  not  due  to  glaciers,  19,  20. 

Subsoil  ice  of  Alaska,  127-130. 

Surface  features  of  glaciers,  11. 

Tacoma,  Mt.,  Glaciers  of,  63-67. 

Taku  glacier,  Alaska,  Description  of,  78-80. 


Taya  inlet,  Alaska,  Glaciers  of,  102. 
Thompson,   G.,   Cited   on   glaciers   of   Mt. 

Shasta,  58-62. 
Thompson,  J.,  Experiments  by,  178. 
Thompson,  W.,  Cited  on  glacial  motion,  178. 
Tide-water  glaciers.  Description  of,  77-96. 
Till,  described,  24. 
Topham,  H.  W.,  Cited  on  Alaskan  glaciers, 

76. 
Topographic  changes  made  by  glaciers,  .30, 31. 
Tyndall,  J.,  Cited  on  glacial  motion,  105, 166. 

Cited  on  rej^slation  hypothesis,  173. 

Tundras  of  Alaska,  Brief  account  of,  120, 130. 
Tunnels  in  glaciers,  Briel  account  of,  15. 
Turner,  J.  H.,  Glacier  naraod  in  honor  of,  93. 
Turner  glacier,  Alaska,  BriDf   account  of, 

02-94. 

Unglaciated  region  in  Alaska,  107,  108. 

Greenland,  134,  146. 

Upham,  Warren,  Cited  on  Drumlins,  25. 

Cited'on  Greenland  glaciers,  155. 

Reference  to  writings  of,  135. 

Vancouver,  Observations  of,  in  Icy  strait, 

90,91. 
Vancouver  system.  Mention  of,  32. 
Variations  in  glaciers,  IIow  to  observe,  150. 

Tb  J  Clerical  consideration  of,  150-160. 

Volcanic  a  ist  on  Alaskan  glaciers,  159. 

Washington,  Evidence  of  retreat  of  glaciers 

in,  149. 
W'lat  is  a  glacier  ?  16-18. 
White  River  glacier,  Alaska,  106. 

Oregon,  68. 

Washinirton,  65. 

Whitney,  J.  I).,  Cited  on  absence  of  glaciers 

in  the  Sierra  Nevada,  51,  52. 
Whitney  glacier,  California,  66. 
Whitney,  Mt.,  California,  Height  of,  37. 
Williams,  W.,  Cited  on  Alaskan  glaciers,  76. 
Wintun  glacier,  60,  62. 
Wood,  A.,  Ascent  of  Mt.  Hood  by,  67,  08. 
Woodward,  R.  S.,  Computations  by,  130.     • 
Wright,  G.  F. ,  Cited  on  glaciers  of  Alaska,  76. 
Observations  on  Muir  glacier  by,  80, 

81. 
Reference  to  writings  of,  37,  135. 

Yakutat  bay.  Glaciers  of,  03. 
Yukon  river.  Work  of  ice  in,  19. 


><^    JAN? 3  l^n3   ^^ 


ANNOUNCEMENTS 


Pm^lPHPIIHIPmWiqpimill 


TIm  b«tt  •ZMnpU  in  thii  country  of  lh«  kind  of  book*  liaat 
goographjr  n«a<U.  —  Tht  N<dion 


THE 

LAKES  OF  NORTH  AMERICA 

By  ISRAEL  C.  RUSSELL 
Professor  of  Geology  in  the  University  of  Michigan 

8vo.    Cloth.    xi+ I2S  pages-    Illustrated. 

RECENT  advances  have  made  physical  geography  almost  a  new 
science.     Professor  Russell  here  presents  a  single  phase,  but  one 
of   great   importance.     The  work    is   based    upon    his   original 
investigations,  and  is  at  once  thoroughly  scientific  in  substance  and 
enjoyably  popular  in  style. 

As  a  text-book  or  reading  book  for  students  in  geography  and 
geology  the  "  Lakes  of  North  America"  possesses  a  unique  value.  Its 
interest  to  the  general  reader  is  enhanced  by  its  illustrations  and  its 
happy  descriptions  of  lake  scenery. 


GLACIERS  OF  NORTH  AMERICA 

By  ISRAEL  C.  RUSSELL,  Professor  of  Geology  in  the  University  of  Michigan 
Author  of  "  Lakes  of  North  America  " 

8vo.    Cloth.    X  +  2IO pages.    Iliustrated. 

RECENT  explorations  have  shown  that  North  America  contains 
thousands  of  glaciers,  some  of  which  are  not  only  vastly  larger 
than  any  in  Europe,  but  belong  to  types  of  ice  bodies  not  there 
represented.  In  the  study  of  the  glaciers  of  North  America,  and 
especially  of  those  in  Alaska,  Professor  Russell  has  taken  an  active 
part ;  and  this  book  not  only  presents  the  results  of  his  own  explora- 
tions but  also  a  condensed  and  accurate  statement  of  the  present  status 
of  glacial  investigations.  Its  popular  character  and  numerous  illustrations 
will  make  it  of  interest  to  the  general  reader. 


DEPARTMENT  OF  SPECIAL  PUBLICATION 


GINN  &  COMPANY  Publishers 


GEOGRAPHIC  INFLUENCES  IN 
AMERICAN  HISTORY 

By  ALBERT  PERRY  BRIGHAM 

Professor  of  Geology  in  Colgate  University,      iimo.     Cloth.      366  pages. 

Illustrated.     List  price,  f  1.15  j    mailing  price,  J!i. 40 


IN  this  new  book  Professor  Brigham  has  presented 
vividly  and  clearly  those  physiographic  features 
of  America  which  have  been  important  in  guiding 
the  unfolding  of  our  industrial  and  national  life.  The 
arrangement  is  mainly  geographical.  Among  the 
themes  receiving  special  treatment  are :  The  Eastern 
Gateway  of  the  United  States,  the  Appalachian  Bar- 
rier, the  Great  Lakes  and  American  Commerce,  the 
Civil  War,  and  Mines  and  Mountain  Life.  Closing 
chapters  deal  with  the  unity  and  diversity  of  Ameri- 
can life  and  with  physiography  as  affecting  American 
destiny. 

The  book  will  be  found  particularly  interesting  and 
valuable  to  students  and  teachers  of  geography  and 
history,  but  it  will  also  appeal  to  the  general  reader. 
The  very  large  number  of  rare  and  attractive  photo- 
graphs and  the  numerous  maps  are  of  importance  in 
vivifying  and  explaining  the  text. 


GINN    &    COMPANY    Publishers 


, 


DAVIS'S  PHYSICAL  GEOGRAPHY 

»v 

WILLIAM   MORRIS   DAVIS. 

Pre/tttor  i^ I'hysical  Cmojirafhy  in  Harvard  Univtriity, 

A'SISTIO   BV 

WILLIAM  IL  SNYDER,  Master  in  ScuHct  in  n'orcitttr  Acadtmy. 


lamo.    Cloth.    438  pagei.    Uluttrated.    For  Introduction,  $1.25. 


-^HIS  textbook  presents  the  leading  principles  of  physical 
^  geography  in  a  form  adapted  to  the  needs  of  pupils  in 
secondary  schools.  The  subject  is  treated  as  dealing  with  "the 
physical  environment  of  man."  The  description  of  the  geo- 
graphical controls  by  which  man's  ways  of  living  are  determined 
constitutes  the  main  theme  of  the  book. 

TIt"  chief  headings  are:  — The  Earth  as  a  Globe,  the 
Atiiiosphere,  the  Oceans,  and  the  Lands.  The  greatest  amount 
of  space  is  given  to  the  subject  under  the  last  heading,  which  is 
divided  into  several  chapters,  following  a  method  of  treatment 
developed  by  the  senior  author  and  thoroughly  tested  in  the 
Harvard  summer  courses  on  physical  geography. 

Especial  care  has  been  taken  to  adapt  the  descriptions  and 
explanations  to  the  capacity  of  pupils  in  higher  schools.  Unusual 
technical  terms  have  been  excluded  almost  wholly.  Geometrical 
and  physical  explanations  have  been  set  apart  in  an  Appendix,  in 
order  that  the  progress  of  pupils  who  have  not  studied  geometry 
and  physics  may  not  be  embarrassed. 

Photographs  of  natural  scenery  have  been  freely  used  for 
illustracions  of  the  actual  facts  of  nature.  Typical  land  forms 
are  shown  in  dra-vings.  Outline  maps  serve  to  give  definiteness 
to  nearly  every  locality  mentioned  in  the  text,  so  that  no  atlas 
need  be  referred  to  when  using  the  book. 


THE  HARVARD  GEOGRAPHICAL  MODELS. 

Designed  by  William  M.  Davis,  Professor  of  Physical  Geography  in 
Harvard  University.  Price,  per  stt  of  three,  $20.00.  Descriptive 
circulars  sent  postpaid  on  application. 


GINN  &  COMPANY,  Publishers. 

Boston.         New  York.         Chicage .         Atlanta.         Dallai. 


, 


Davis'  Elementary  Physical  Geography 


By   WILLIAM    MORRIS    DAVIS 

Author  of  Davis'  "Physical  Geography  "  and  Professor  of  Geology  in 
"  /  University 


Harvd 


lamo.    Cioth.    vlH  +  401  pages  +  6  color  charts  +  16  pages  of  maps. 
Illustrated.    Lii>t  price,  $1.25. 


HE  "  Elementary  Phyncal  Geography  »  is  a  new  book 
by  Professor  W.  M.  Davis,  the  first  authority  in  the 
United  States  in  the  field  of  physical  geography.  It 
retains  the  characteristic  features  of  the  author- 
earlier  work,  "  Physical  Geography,"  but  is  much  less  difficult 
and  Is  admirably  adapted  for  ure  with  younger  pupils. 

The  plan  of  this  volume,  like  that  of  its  predecessor,  is  to  give 
the  problems  of  physical  geography  a  rational  treatment.  The 
object  of  this  method  is  not  simply  to  explain  physiographic 
facts,  but  to  increase  the  appreciation  of  the  facts  themselves  by 
associating  them  with  their  causes  and  their  consequences.  This 
relation  is  not  presented  merely  as  an  afterthought  in  a  detached 
chapter  at  the  end  of  the  book ;  it  accompanies  the  presentation 
of  the  facts  themselves. 

The  chfipter  on  the  Atmosphere  has  been  considerably  expanded, 
and  an  entirely  new  chapter  has  been  added  on  the  Distribution 
of  Plants,  Animals,  and  Man,  considered  from  a  physiographic 
standpoint.  The  questions  at  the  end  of  each  chapter,  prepared 
by  an  experienced  high-school  teacher,  will  be  found  most  useful 
in  class  room  work  witli  this  book. 

Especially  notable  sre  the  illustrations,  which  include  nearly 
two  hundred  splendid  woodcuts,  five  pages  of  charts  in  color,  and 
nineteen  full-page  half-tone  plates  from  rare  photographs. 

The  Nation,  July  3,  1902  :  Taken  all  in  all,  this  seems  the  most  satisfactory 
elementary  text-book  in  physical  geography  yet  published.  Certainly  in  its 
treatment  of  the  land  it  has  not  been  surpassed  unless,  perhaps,  by  the  author's 
larger  work  [ "  Physical  Geography  "]. 


GINN  &  COMPANY  Publishers 


^•■ilpilp* 


THE  ELEMENTS  OF  GEOLOGY 

By  WILLIAM  HARMON  NORTON 

Professor  of  Geology  in  Cornell  College,  Mt.  Vernon,  Iowa 


8vo.     Cloth.    461  pages.      Illustrated.      List  price,  |!  1.40  ;  mailing  price,  $1.55 


THE  essentials  of  the  science  of  geology  are  treated 
with  fullness  and  ample  illustration  in  this  text-book 
for  beginners.  By  limiting  his  discussion  chiefly  to  this 
continent  the  author  has  ueen  able  to  devote  a  large 
amount  of  space  to  the  principles  which  he  describes.  The 
following  characteristics  are  important. 

1.  The  outline  is  exceptionally  simple.  Under  the  leading  geological 
processes  are  grouped  the  rock  structures  and  land  forms  of  which 
they  are  the  cause. 

2.  The  inductive  method  is  emphasized  throughout.  Concrete 
examples  are  given  large  space  as  the  basis  of  generalizations  of  the 
science.  Numerous  exercises  and  problems,  many  of  which  are  in  the 
form  of  diagrams,  are  designed  to  train  the  pupil  and  to  test  his 
knowledge. 

3.  The  cycle  idea  is  made  prominent,  and  both  the  records  of  erosion 
and  those  of  sedimentation  are  given  special  attention. 

4.  In  historical  geology  a  broad  view  is  affoii'  ;d  of  the  development 
of  the  North  American  continent  anu  of  the  evolution  of  lift  upon  the 
earth.  Only  the  leading  types  of  plants  and  animals  aia  mentioned, 
and  specia'  attention  is  givt  n  to  those  which  mark  the  lines  of  de-ocent 
of  forms  now  living. 

The  book  is  designed  for  use  in  high  schools  and  acad- 
emies, and  may  also  be  found  useful  in  short  elementary 
college  courses. 


GINN  &  COMPANY  Publishers 


T'T'^^'"''?'''''"^^^'^'^^'^'^'^™™^''^^ 


